Chapter 1
Cell Theory:
All living things are composed of cells, cells are the basic functional unit of life, calls arise only
from preexisting cells, cells carry genetic information in the form of DNA passed from parent to
daughter cell.
Microscopy:
magnification (enlarging) and resolution (the ability to differentiate two closely placed objects)
Compound light microscopes: the magnification is the lens multiplies by the objective.
The diaphragm controls the amount of light to pass through the lens.
The phase constant microscope uses different refractive indices among different sub-cellular
structures to visualize living organisms.
Electron Microscope-allows us to see atomic level, using electrons, light can only be as good as
wavelengths of light which are only good up to nanometers.
Autoradiography- uses x rays and decay to obtain an image. On a cellular level compounds that
the cell uses can be made with radioactive materials.
Centrifuge measured by how many times greater than gravity and has more impact on the more
dense.
Prokaryotes vs Eukaryotes:
All bacteria are prokaryotic, the cell wall does not contain any membrane bound organelles, the
dna is circular and is concentrated in the nucleoid region, they also have smaller circular pieces
of DNA called plasmids, which replicate independently and lead to fast evolution and resistance
to antibiotics.
Both pro and eu contain ribosomes.
pro can only be unicellular.
Cocci bacteria are spherical while rod shaped bacteria are bacilli.
All bacteria also contain a cell membrane and cytoplasm, some have flagella, which eukarya
like sperm also have for motility.
Eukaryotes- are suspended in cytosol which is a semifluid and allows for diffusion throughout
the cell. DNA is on chromosomes which are linear and found in the nucleus.
The cytoskeleton is made up of actin filaments, intermediate filaments and microtubules, which
allow for movement inside the cell and provide a framework for anchoring organelles within the
cell.
Microfilaments are made up of actin that are the smallest of roads and are used in muscular
contraction, move materials in Cell, and cause amoeboid movement.
Microtubules are hollow and are polymers of tubulin proteins and radiate through cell providing
longest roads for transport and structural support, they are involved in cell division, and are the
structural basis for cillia and flagella
Intermediate filaments help maintain shape of cytoskeleton.
The cell membrane is a phospholipid bilayer, and is based on the theory of the fluid mosaic
model. ITs studded with proteins and lipid rafts that control the movement of solutes, and are
mobile in the membrane. THe phospholipids have a hydrophobic tail and a hydrophilic head,
facing the external. CHolesterol molecules regulate the stiffness.
The proteins play a role as transport proteins, allowing polar and ions to move across while cell
adhesion molecules allow cells to recognize each other.
Nucleus is surrounded by the nuclear member (envelope) which is a double membrane that
contains distinct environment from cytoplasm. There are also nuclear pores that allow for
selective exchange of material. THe DNA is wound up around histones and then wound into
linear strands called chormosomes. The nucleolus is a subsection where the ribosomal (rRNA)
is snythesized.
Ribosomes take orders from nucleus and make proteins. There are bound ribosomes and free
travelling ones but all use the endoplasmc reticulum to send away proteins.
The ER can be smooth or rough, the rough has ribosomes. THe smooth ER wroks towards lipid
synthesis and detoxification of drugs, whereas the rough is more involved in production of
proteins.
The golgi apparatus often repackages materials from the smooth ER and often send them in
secretory vesicles that release the contents to the exterior through exocytosis.
Vacuoles are bigger than vesicles but both are used to transport and store material.
Lysosomes take material brought in by endosomes, and use hydrolytic enzymes at pH5 to break
down materials. THey can cause autolysis which is cell suicide also known as apoptosis.
Mitochondria-contains an inner and outer layer, the inner membrane contains foldings called
cristae, increasing surface area for the electron transport chain, the inner membrane encloses
mitochondrial matrix which contains enzymes important for respiration. Between the membranes
is the intermebrane space. THey are semiautonomous with their own genes and indpendent
replication via binary fission. THey are only passed on through the mother. Its DNA is circular.
MIcrobodies catalyze specific reactions by gathering enzymes and substrates. Peroxisomes
create hydrogen peroxide which is used to break down fats and catalyze detoxification in hte
liver. Glyoxysomes convert fats to usable fuel (sugars).
CHlropolast contain chlorophyll and generate energy and O2 using water CO2 and sunlight and
also have own DNA and also evolved through symbiosis.
Cell walls are for defense and stability, plants have a wall of cellulose and fungi have chitin,
animals do not.
Only animal cells have centrioles which are a type of microtubules that are important for spindle
formation.
Simple diffusion like osmosis, when one solution is hypotonic to another it will swell, hypertonic
is when shrivel and isotonic is whe equimolar, remember its based on concentrations. AN
exmaple is red blood cell in water, RBC has higher concentration and bursts.
Facilitated Diffusion-is diffusion for molecules that are loarge, polar or charged, go throug
membrane proteins but dont use energy.
Active transport is net movement of a solute against concentration gradient.
Pinocytosis is the endoyctosis of fluids and small particles and phagocytosis is th eingestion of
large molecules, the amterial can be toxic because will be in vesicle. Exocytosis is the reverse
Epithelial tissue are thsoe that cover the body and line the cavities, protecting from invasion,
and desiccation (drying up). IT also is inovlved in absorbtion secretion and sensation.
Connective tissue are made up of bone, cartilage, tendons, ligaments, adipose tissue and
blood.
Nervous tissue, use electrochemical gradients to allow cellular signaling
Muscle TIssue-there is skeletal smooth and cardiac
Viruses are accllular composed of nucleic acids surrounded by a protein coat, they are smaller
than bacteria. Genetic info can be circular linear, single or double stranded and dna or rna. The
protein coat is called the capsid. They cant reproduce interdependently and are known as
obligate intracellular parasites.
After hijacking a cells machinery a virus will replicate and turn out new copies of itself called
virions. Bacteriophages are viruses that specifically target bacteria, simply injecting genetic
material into the bacteria.
Chapter 2
Exothermic reactions have a negative change in H. Enzymes dont change the enthalpy or
equilibrium of a reaction but only the rate. Furthermore, all the reactions are reversible.
THe substrate is the molecule which the enzyme acts upon. When the two are together its
called the enzyme substrate complex. The substrate is held in the active site.
Lock and key theory is based on the idea that the substrate is already the correct shape for the
substrate, while the induced fit theory says the substrate endoethermically bends the enzyme
and exothermically releases it later.
Enzymes sometimes require cofactors, non proteins, to be effective. WIthout the cofactor they
are known as apoeenzemes, whereas containg they are called holoenzymes. The tightly bound
cofactors are known as a prothetic group.
COfactors can be small metal ions or small organic groups aka coenzymes.
Once an enzyme has reached saturation it goes at maximum velocity and no amount of adding
concentration of substrate will raise velocity.
Km is where the substrate conenctration intersects with 1/2 of the maximum velocity. From that
point on adding substrate will not change the velocity much, removing will.
ES reactiosn double in rate every 10 degrees celsius until 37 and then quickly die off. For
enzymes that circulate in the blood the optimal ph is 7.4. pH of 7.3 is acidosic, This is not the
case in digestive tract, and pancreatic enzymes in the samll intestine work around 8.5.
Allosteric effects
Allosteric sites are locations on allosteric enzymes that can regulate the availability of the active
site. The allosteric sites can by filled with activators or inhibitors, which cause conformational
shifts.
Feedback inhibition-tHe activity of an enzyme can be regulated by one of its products. This can
work by a product binding to an enzyme earlier in the process.
Reverse Inhibition: Competitive inhibition is when an inhibitor competes with the substrates for
the active site. It can be overcome by adding substrate. Noncompettive- is when inhibitors bind
to the allosteric site and cannot be overcome by adding substrate.
Irreversible inhibition is when an inhibitor binds to the axtive site irreversibly, asprin does this for
pain regulators.
Certain enzymes are dangerous so they are secreted as inactive zymogens, which contain an
active and regulatory domain. The reg domain must be removed or altered to expose the active
site.
Chapter 3
Autotrophs are organisms that are capable of using the suns enegry to create organic
molecules, that store energy in bonds. All energy for living organisms is derived from the sun.
An example is photosyntehsis by plants. Heterotrophic organisms break down organic
molecules made by palnts.
Glucose forms a ring structure known as pyranose in either alpha or beta configurations.
GLucose formation is endothermic it requires 6Co2+6H2O and yields C6H12O6 and 6O2.
Cellular respiration is just the reverse of this reaction, with energy being release by breaking the
bonds.
ATP, NAd+ and FAD serve as high energy electron shuttles between the cytoplasm and
mitocondria.
ATP has a nitrogenous base adenine, a sugar ribose, and three phosphate groups. The loss of
1 or 2 phosphate groups gives 7 or 14 kcal/mol.
NAD and FAD are coeenzymes that accept high energy electrons during glucose oxidation and
transfering the electrons through the electron transpor chain. The electrons are usually
transferred in the form of hydride ions. So NAD+ and FAD are reduced to NADH and FFADH2
and are then oxidized. FAD can pick up two electrons.
SO in order for hetereotrophic cells to have energy they undergo glycolysis and cellular
respiration.
GLycolysis occurs in the cytoplasm, wiht or w/o O2. At step 4 the glucose is split into two
isomers dihydroxyacetone phosphate and glyceraldehyde 3 phosphate, so now every step
occurs twice as much. The final output is two molecules of three carbon pyruvate. Steps 1 and 3
each require one molecule of ATP but steps 6 and 9 each produce 2 moelcules of ATP so we
hav ea net gain of 2. The direct gain of ATp from ADP and P is known as substrate level
phosphorylation. Also two NAD+ molecules are reduced to 2 NADH molecules.
In anaerobic organisms the pyruvate undergoes fermentation. SOme cells are obligate
anaerobe/aerobic vs faculative wehre a cell prefers a certain environment.
Fermentation is necesary to oxidize NADH so glycolysis can be restarted. Pyruvate is reduced
to either ethanol or lactic acid. Fermentation actually refers to all th steps of glycolysis plus the
reduction of pyruvate.
Alcohol Fermentation=pyruvate is decarboxylated to CO2 and Acetaldehyde, and then reduced
by NADH to ethanol and NAD+. (Takes place in yeast and some bacteria.
Lactic Acid Fermentation-takes place in fungi, bacteria and our own muscles. SO not all
pyruvate molecules can be used for cellular repsiration right away, so pyruvate and NADH build
up. TO keep muscles working the NADH must be oxidized. Lactic acid is produced instead of
ethanol and produced burn are lowering of pH. Once O supply catches up with demand, lactic
acid can be converted back to pyruvate is a process known as Cori cycle, the amount of O
required is known as O debt.
Cellular Respiration-generates 36-38 ATP per molecule of glucose, O is the final electron
acceptor. There are three phases:
Pyruvate Decarboxylation- only occurs in aerobic conditions but does not require O. Pyruvate s
transported from teh cytoplasm into the midochondrial matrix where it is decarxoylated, loss of
Co2. The remaining acetyl group is bouded to xoenzyme A, hence the name acetyl-CoA. For
each acetyl one NAD+ is reduced.
Citric Acid Cycle (AKA Krebs Cycle, tricarboxylic acid cycle) starts with acetyl CoA and
oxaloacetate to generate citrate 6C. Through a series of reactions, two Co2 molecules are
released and oxaloacetate is regenerated. Each turn of the cycle generates one ATP via
substrate level phosphorylation, along with 3 NADH and one FADH2 molecules. 2 molecules of
water are also used for each acetyl coA molecule.
The coenzymes then transport the electrons to the transport chainon the inner mitochondiral
membrane, where ATP is produced via oxidative phosphyrlation.
Electron Transport Chain:
Cytochrome complexes resemble hemoglobin in that they each contain a central iron atom that
undergoes reversible redox reactions as electrons bind and release.
The first complex is NADH dehydrogenase and NADH gives itse elctron to FMN, which are
passed to carrier Q (a small hydrophobic moelcule, not an enzyme like the rest), which passes
teh leectron to complex II b-c1 complex which passes them to IV, the cytochrome oxidase
complex. Oxygen takes the electrons from the last cytochrome in the complex as well as two
protons to mkae water. Each NADH generated 3 ATP, while FADH2 only makes 2. FADH2 gives
its electron driectly to carrier Q. Cyanide blocks the final transfer of electrons to O2, and DNP
destroys the mitochondrions ability to generate a proton gradient.
ATP generation and proton pump: As the reduced carriers give up electrons free protons are
passed into the mitochondrial matrix where they accumulate, the ETC pumps these ions out of
the matrix into the intermembrane space, the electrochemical gradient drives H+ passively back
across the mitochondrial membrane, known as proton-motive force. However, the protons cant
make it through the memberane because they are charged. Instead they use channels, called
ATp synthases (enzyme complexes). As the H ions pass through the energy released allows for
phosphorylation of ADP back to atp, oxidative phosphrylation.
Review: Glycolysis involves investment of 2 atp and generation of 4 atp, with 2 nadh, pyruvate
decarboxylation yields two nadh, one for each pyruvate, each turn of the TCA gives three nadh
and on fadh2 butmultiply by two becuase two for each glucose, ATP from nadh yields 28 ATP,
because the two from glycolysis only yield two atp bc like FADH they give electrons driectly to
carrier Q. Prokaryotes dont ahve to get through mitochondiral membrane so save two atp and
make 38.
When low glucose levels we use carbs, proteins and fats.
Carbs are broken down during digestion and then stores in the liver as a polysaccharide,
glycogen, which is converted to glucose 6 phosphate when needed.
Fats are stored in adipose tissue as triglycerides, three lon chain fatty acids are esterified to a
glycerol which can be converted to PGAL a glycolytic intermediate. Fatty acids are activated in
cytoplasm and are transporte dto mito matrix to undergo rounds o fbeta oxidation where acetyl
coa is geerated, We can do 24 rounds of beta oxidation generatign 24 NADH and 24 FADH,
Proteins are polypeptides made of amino acids, the removal of the amine by transaminases
results in alpha ketoacids which can be converted to acetyl coa.
Anabolic-to build up molecules like photosynthesis, Catabolic-break down like digestion
Chapter 4
Reproduction:
Unicellular organisms reproduce through division while multicellular organisms replace cells that
are ready to retire through cell division.
Prokaryotes divide via binary fission which is asexual, the DNA attaches itself to the cell
membrane and duplicates itself while the cell grows, the cell membrane then invaginates
creating two identical daughter cells.
Eukaryotic autosomal cells are diploid, 2n, while sex (germ) cells are haploid, n. We have 46
chromsomes, 23 from each parent.
The cell Cycle
Interphase, is the longest part of the cell cycle. There are three phases.
G1 -cells create organelles for energy and protein production while doubling in size. The
transition to the S stage is governed by a restriction point. The checkpoint makes sure
everything is in order before continuing.
S-replicate or synthesize genetic material sot hat each duaghter will ahve identical copies. After
each chromosoem consists of two identical copies, called chromatids boud together by the
centromere. The ploidy is still the same even though there are double the number of
chromatids.
G2- quality control making sure there are enough organelles and cytoplasm to make two
daughter cells.
During interphase DNA is in the form of chromatin which is more spread out bc it needs to be
transcribed but during M its preferable for the DNA to be tightly bound so as not to lose any.
M Stage (Mitosis)-Mitosis as well as cytokinesis. We have prophase, metaphase, anaphase and
telophase. Cytokinesis is the actual splitting.
centrioles are organelles that regulate chromsome movement. They are outside the nucleus in a
region known as the centrosome and are responsible for the correct division of DNA> Durign
prophase the centrioles migrate to opposite poles of the cell and begin to form spindle fibers,
made from microtubules. The attachment point on the centromers are asters.
Prophase-chromsomes condense adn centriole pairs seperate and move to poles and the
spindle apparatus forms between them. The nuclear membrane dissolves, while the nucleoli
become less distinct. Kinetochores with attached kinetochore fibers appear at the chromosome
centromere.
Metaphase-the centriole pairs are not at opposite poles of the cell, and the kinetochore fibers
interact with the fibers of the spindle apapratus to aligh the chromosmes at the metphase plate,
which in the middle of the two poles.
Anaphase-centromers split and pulled towards opposite ends by the shortening of the
kinetochore fibers. Telmoeres are the last part to split they are repetitive dna on chromsome.
Telophase and cytokinesis-the spindle dispapears a nuclear membrane reforms and the
nucleopli reappear, the chromsomes uncoiland then cytokinesis occurs.
Each cell can undergo 20-50 splits before cell death. After that the cell will incorporate errors.
muscles and nerves never divide. while cancer cells divide continuously.
Asexual Reproduction:
Binary Fission-THe circular chormosome attaches to the cell wall, replicates, and divides into
two equal daughter cells. IT is rapid.
Budding-Equal replication followed by unequal cytokinesis. IT takes place in some small
eukarya
Regeneration-primarily in lower organisms is accomplished by mitosis. Livers in human can
regenerate with a little.
Parthenogenesis-whereby an adult organisms develops froma n unfertilized egg. They will be
haploid.
Sexual Reproduction-Unique offspring! specialized sex cells are gametes and are produced by
meiosis. MItosis results in 2 identical diploid daughter cells where as meisos yields 4 different
haploid gametes, somatic cells use mitosis, where as gametocytes undergo meiosis.
The first division results in reductional division, where the chromosomes are seperated. Meiosis
II is similar to mitosis in that it results in seperation of sister chromatids and is known as
equational division. The rsult is four genetically unique haploid cells.
Prophase I-After condensing homologous chormsomes come together and intertwine ina
rpocess callled synapsis. The four chromatids in the synapsis are referred to as a tetrad.
Homologous chromosomes may break at the point of snyapsis, aka chiasma, and exchange
DNA, in a process known as crossing over. ITs not between chromatids ont he same
chromsome because they are identical.
Metaphase I-the homologous pairs line up at the equatorial plane and each pair attaches to a
separate spindle fiber by its kinetochore.
ANaphase 1-homologous pairs seperate and are pulle to opposite side, in a process known as
disjunction. The chromosomes can be from male and female in both new cells.
Telophase 1-nuclear membrane forms around each new nucleus, Each chromatid is the same
except for the genetic recom on one. The cell divides by cytokinesis, and there may be a short
interkinesis where chormosomes partially uncoil.
Meiosis II-is the same as mitosis
In females only one of the four haploid daugter cells are produced by gametes.
Random distribution of chromosome sin emisois with crossing over in prophase I enable
different genetic combinations.
HUman sexual reproduction:
Haploid sperm and ovum, produced by gonads, fuse during fertilization to form a single cell
zygote in the fallopian tubes.
Testes have twofunctional components the seminferous tubules and the interstitial cells (cells of
leydig).
Sperm are produced in the highly coiled seminefrerous tubules where they are nourished by
sertoli cells. The cells of leydig secrete tesosterone and other male sex hormones (androgens).
The testes are located in the scrotum, which is cooler.
As sperm mature they pass through the epididymis and gain motility in the form of a flagellum
and are stored until ejaculation. The maturation takes 72 days. It eventually passes through the
vas deferens, ejacuatory duct, urethra and penis.
The seminal fluid is produced by seminal vesicles, prostate gland and bulbourethral gland. THe
combination of sperm and seminal fluid is semen.
Seminal vesicles contribute fructose to nourish sperm, and the prostate gives the alkaline
properties.
Spematogensis: occurs in seminerferous tubulues. The diploid cells are known as
spermatogonia. They replicate their genetic material and develop into primary spermatocyes.
The first meiotic division results in haploid secondary spermatocyes. Then they ungergo
meitosis II to generate spermatids which beome spermatazoa. The sperm consists of a head
containing genetic material, a midpiece to generate energy from fructose for motility and a tail
for motility. They have lots of mitochondria. Each sperm head is covered by a cap known as
acrosome. It is derived from the golgi apparatus and is necessary to penetrate the ovum. After
pub, 3 mill produced per day.
Female Reproductive Anatomy:
Ovaries located below digestive tract and contain thousands of follicles which are multilayers
sacs that contain, nourish, and protect immature ova. One egg/month released to peritoneal
sac, moves into fallopian tube (oviduct), which is lined with cilia, fallopian tubes are connected
to the uterus, which is the site of detal development. The lower end of the uterus knwon as the
cervix connects the vaignal canal, the external vagina is called the vulva.
Oogenesis is the production of female gamets, all formed during fetal development. At birth
females have prediffrentiated cells known as primary oocytes which are 2n and are frozen in
prophase 1. Once a woman reaches menarche (first menstration) oen primary oocyte complets
meisosis I per month producing a secondary oocyte and a polar body. Almost no cytoplasm is
give to the plar body, which does not divide any farther. The secondary occyte is frozen in
metaphase II unless fertilization occurs.
2 cell layers surround oocytes, the zona pellucida and teh corona radiata. fertilization occurs
when sperm penetrate these layers, with the help of acrosomol enzymes. The secondary oocyte
undergoes a second division leading to a mature ovum and another polar body which dies.
So until menopause women ovulate one secondary oocyte every 28 days. After menopause the
ovaries become less sensitive to their stimulating hormones and eventually atrophy. Since ovary
production contributes to a negative feedback loop for FSH and LH when women go through
menapause the levels hoot up.
Fertilization:
seondary oocytes can be fertilized within 24 hours of ovulation. Sperm surivve for on or two
days in vag. IF fertilize forms a zygote. IF acrosomal enzymes digest corona radia and
penetrate zone pellucida first sperm that contacts iwth secondary oocytes cell membrane forms
a tubleike structure known as the acrosomal apparatus, which etends to and penetrates the cell
membrane and its nucleus enters the ovum makign it no longer a secondary oocyte. A cortical
reaction takes place and ca ions ar released in cytoplasm making a fertilization membrane
which is impenaterable for other sperm.
Monozygotic twins develop when a single zygote splits into two, they have same gentic material,
but if split incmeplete attached.
Dizygotic twins is if two eggs are relased in cycle and both are fertilized. They are only as similar
as two siblings.
Chapter 5
After fertilization in the fallopian tubes the zigote moves to the uterus for implantation and
undergoes mitosis, durin ga process called cleavage. The first cleavage creates an embryo,
splitting doesnt increase size, but does raise the ratio of surface area to volume and nuclear to
cytopalsmic ratios.
Indeterminate cleavege results in cells that can still develop into complete organisms, versus
determinate cleavage. The first cleavage is at 32 hours followed by 60 and 72 t which point it is
an eigt cell embryo in the uterus.
After more divisions it becomes a morula-solid mass of cells.
Then the morula undergoes blastulation and forms a blastula, which is characterized by the
presence of a hollow fluid filled inner cavisty known as the blastocoel. In mammals the blastula
is known as a blastocys and has two cell groups, the trophoblast and inner cell mast. THe
trophoblast give rise to the chorion while the inner cell mass give rise to the orgnaism. (days
5-8)
Now the blastocyst must implant in the endometrium of the uterine wall. Progesterone promotes
proliferation of endometrial mucosal layer to help the embryo implant. Additionally embryonic
cells secrete enzymes that burrow in the lining to all ow implantation, connecting to maternal
circulation for nutrient and gas exchange. As we plant a seed, embryo, into the ground,
endometrium, soild must be fertile, progesterone, and a shovel to plant the seed, proteolytic
enzymes (enzymes which break down proteins), and as the tree grows it makes roots, the
placenta.
Gastrulation-the generation of 3 cell layers. From the study of sea urchins we know that during
gasturaltion a small invagination in the blastula begins eliminating the blastocoel, formings a 2
layered gastrula, the inner layer is the endoderm, the outer is the ectoderm and the cavity is the
archenteron which becomes the gut. THe opening of the archenteron is called the blastopore. In
deuterostomes, such as humans, the blastopore developes into the anus. In protostomes it
becomes the mouth. SO the endoderm is what lines the archenteron, eventually some cells
migrate into the area between the derms and is the mesoderm.
THe ectoderm develops into the integument (protects body from damage, including epidermis,
hair, nails, epithelium of the nose mouth and anal canal, lens of the eye and nevrous system.
SO the ectoderm is the attractoderm.
The mesoderm is the musculoskeletal system, circulatory system, excretory system, gonads,
and muscular and connective tissue coats the digestive and repsitory system. THis is th
means-o-derm, including heart and bones, and vessels.
Endoderm-is the epithelial lining of the digestive and respiratory tracts, lungs parts of the liver
and pancrease, thyorid bladder and distal urinary and reproductive tracts. This is the endernal
system,
Embryonic stem cells are derived from early stage embryo, probably inner cells and are
pluripotent.
In the human, a week after fertilization, the embryo contains 100-150 cells in the form of a
blasula of which the outer cell mass becomes the placenta and the inner cell mass becomes the
fetus and after 3 weeks forms the gastrula.
The kidney is derived from the mesodermal cells despite being internal organs b.c they are not
really in the abdomen and are external to the peritoneum (gut sac) making them retroperitoneal
organs.
Selective Transcription allows for selectivity of cells. It is related to the concept of induction,
which is the ability of a certain groups of cells to influence the fate of other nearby cells.
Chemical substances called inducers are passed from the organizing cells to the responsive
cells.
Neurulation-is the developmen to fth enervous system and begins once the three germ layers
are formed.
The nervous system develops from the ectoderm but its on the outside of the gastrula. So the
cell sare induced to migrate inwards. First a rod of mesodermal cells known as the notochord
forms along the long axis of the organism. These cells induce a group of ectodermal cells to
slide inward to form neural folds, which surround a neural groove. The neural folds grow
towards one another until they fuse into a neural tube, which gives rise to the central nervous
system. At the tip of each neural fold are neural crest cells. The cells migrate outward to form
the peripheral nervous system including sensory ganglia, autonomic gnaglia, adrenal medulla
and Schwann cells. Finally ectodermal cells will migrate around the neutral tube and and
surrounding the tube.
The placenta and umbilical cord develop in the weeks after fertilization. The placenta is formed
from extra-embryonic membrane called the chorion which develops from trophoblast cells and
provide nutrition for hte fetus. The other three extra-embryonic membranes are the allantois,
amnion and yolk sac. The allantois is surrounded by the amnion which is a thin tough
membrane filled with amniotic fluid which serves as a shock absorber. Beyond that is the yolk
sac which is the site of early blood vessel development and the outermost layer is the chorion.
Chorionic villi eventually grow into the placenta and support maternal fetal gas exchange. THe
umbilical cord is surrounded by a jelly like matrix and is the initial connection between mother
and fetus.
The placenta is the site of nutrient, gas and waste exchange. No mixing of blood is possible
because of different types. Water, glucose, amino acids and inorganic salts are transferred via
diffusion. In addition to a gradient for O2 the fetal hemoglobin (Hb-F) also has greater affinity
than Hb-A.
The placental barrier also provides immune protection bc many foreign particles are too large to
cross the placental barrier by diffusion, however viruses like HIV, alcohol and toxins are not.
Fetal Circulation:
In the fetus the lungs and liver are under developed so the placenta carries out their functions.
BLood must be kept away from the lungs. This is accomplished with two shunts within the heart,
the foramen ovale, which connects the right and left atria. Blood enters the right atrium from the
superior vena cava flows into the left atrium instead of the right ventricle. For blood to travel
from the righ tto the left there must b ea pressure differential, pressure higher in right and is
accomplished by the foramen ovale, which must be shut for the adult heart to function porperly.
However, the valve connecting the right atria with the ventricle is not entirely shut so some blood
flows in. THe ductus arteriousus shunts leftover blood from the pulmonary artery to the aorta
based on pressure.
The liver which generally detoxifies, stores sugar etc... it cant do all of this since its still
underdeveloped and gets help from the placenta. SO the ductus venosus shunts a lot of the
oxygenated blood from the umbilical vein to the inferior vena cava so that the liver does not
steal the O2 from the rest of the body. Instead the liver gets its O2 from arteries leaving the
heart.
Arteries take blood away from the heart and veins bring it to the heart. So umbilical arteries
carry deoxygenated blood.
Gestation-(pregnancy) lasts 266 days for humans, the bigger the animal the longer and fewer
the offspring.
During the First trimester the major organs begin to develop. The heart begins to beat at 22
days and soon afterwards the eyes, gonads, limbs and liver start to form. During the seventh
week the cartilagnious skeleton begins to harder into bone. By the end of 8 weeks most organs
have formed the brain is developed and the embryo is referred to as a fetus. And at end it is 9
cm long.
During the second trimester-basically just grows and starts to look human at end its about 30-36
cm long.
During the third trimester rapid growth brain development, during the 9th antibodies are
transported by highly selective active transport from mom to fetus for protection against foreign
matter in preparation for after birth. Growth rate slows and becomes less active due to space
constraint.
Birth ultimately arrises from rhythmic contractions of uterine smooth muscle, coordinated by
prostaglandins (type of lipid) and the peptide hormone oxytocin. Three phases, cervix thins and
amniotic sac ruptures, water breaking, next the strong uterine contractions result in birth, finally
placenta and umbilical cord are afterbirthed.
Review:
Blastula has the greatest nuclear to cytoplasm ratio becuase of lots of division without growth.
The thyroid is part of the endoderm
When a baby is born Hb-A, becuase starts breathing resistance in pulmanary vessels
decreases, which causes an increase in blood flow, and pressure in right atrium increases,
Brain develops in first trimester so tetrogens are worst then.
hCG is a hormone made by embryo and small enough to diffuse into mothers blood, as is CO
but not not white blood cells.
Some blood must reach lungs because nourish the developing lungs.
The blood delivered via the aorta will have a lower partial pressure of O2 than blood delivered to
the lungs, becausre oxygenated and deoxygenated blood mix in the foramen ovale.
The ductus venosus degenerates over time, completely 3 months after birth.
The placenta releases progesterone, hcG and estrogen, and acts as an endocrine gland, but
not LH which is secreted during menstrual cycle by anterior pituitary to stimulate ovulation.
Chapter 6
Exoskeletons encase whole organisms and are common for arthropods-shed to grow.
Vertebrates have endoskeletons.
The axial skeleton consists of the skull, vertebral column, and rigcage while the appendicular
skeleton consists of arms, legs, pelvic and pectoral girdles. The skeleton is composed of
cartilage and bone.
Cartilage is more flexible, consisting of a firm elastic matrix known as chondrin , secreted by
chondrocytes.
Adults have cartilage where need flexibility like external ear, nose, larynx, trachea and joints.
Arthritis is the degradation of the cartilage. It is also relatively avascular without blood and
lymphatic vessels.
Bone is harder, stronger but light. The adult has 206 bones.
There is compact bone, which is strong and compact and spongy or cancellous bone which
looks like a sponge. The latter consists of bony spicules known as trabeculae. The cavities are
filled with bone marrow which can be red or yellow. Red is filled with hematopoietic stem cells
which generate all cells in blood. Yellow is mainly composed of fat and is inactive. Hemo means
blood and poisesis means to make.
Appendicular bones are typical long bones characterized by cylindrical shafts called diaphyses
and dilated ends called epiphyses. The peripheries are composed of compact bones while
internal of diaphyses is full of marrow while epiphyses have a spongy bone core inside their
compact bone sheath to disperse force better. The epiphyseal plate seperates the epiphysis
from the diaphysis, which is a cartilaginous structure and the site of longitudinal growth. A
fibrous sheath called periosteum surrounds the long bone to protect it as attach to muscles.
They are also capable of differentiating into bone forming cells and is necessary for bone growth
and repair.
Compact bone is strong because of the bone matrix, which is composed of collagen,
glycoprotiens and other peptides as well as Ca, phosphate and hydroxide ions that harden
together to form hydroxyapatitte crystals. Other minerals like Na, Mg, and K are also stored in
the bone.
Strong bones require uniform distribution of inorganic material. The matrix is ordered into
structural units known as oseons or Haversian systems. Each osteon encircles a central
microscopic channel known as a Haversian canal surrounded by concentric circles of bony
matrix called lamellae. The canals contain blood vessels, nerve fibers and lymph that keep the
bone in peak condition. In between the lamealla are lacunae which house mature bone cells
known as osteocytes, which are involved in bone maintenance. Each lacunae is interconnected
by canaliculi which are little canals that allow for exchange of nutrients and waste between them
and the haversian canals.
Endochondral ossification is the process of cartialge turning into bone.
Bones can also be formed through intramembraneous ossification in which embryonic
connective tissue (mesenchymal tissue) is transformed into and replaced by bone.
Osteoblasts build bone and osteoclasts resorb bone which allows for the maintenance of bone.
During bone reformation, essential ingredients like calcium and phosphate are obtained from
the blood. During resorption (break down) the ions are released into the bloodstream. Bone
remodeling is affecting by exercise and use.
Joints-made of connective tissue and are either movable or immovable. Movable work like
hinges, stregthened by ligaments which are pieces of fibrous tissue that connect bones and
have a synovial capsule that encloses the actual joint cavity. Synovial fluid eases the movement
of the bones.
Articular cartilage coats the articular surfaces of the bones so the impact is restricted to the
lubricatd joint cartilage region.
Immovable joints like in the skull fix bones together
Muscles come in skeletal, smooth, and cardiac.
The somatic nervous system allows for controlled movements. The skeletal muscle system
allows for such movements. Muscles are made of repeating units, the basic contractile unit is
the sacromere and are put together to form myofibrils, which are surrounded by a covering
known as sacroplasmic reticulum, which contain much Ca2+. Outside the Sacroplasmic
reticulum is the sarcoplasm, modified cytoplasm, and outside is the cell membrane known as
the sarcolemma. Many myofibrils can be contained within one myocyte (muscle cell). Many are
multinucleated due to fusion of several embryonic uninucleated cells. The nuclei are on the
peripheri and the muscle is simply a parallel arrangement of many myocytes. The sacrolemma
is capable of propgating an action potential. A system to T-tubules is connected to the
sacrolemma and oriented perpendicularly to the myofibrils allowing for ions to flow.
skeletal muscle is striated due to alignment of Z lines. They consist of red and white fibers, red
muscle fibers are slow twitch which have a high myoglobin content and primarily derive their
energy aerobolically. Myoglobin is similar to hemoglobin but consists of a single polypeptide
chain, it binds O more tightly than hemo.
White fibers are fast twitch and are anaerobic and have less myoglobin. Red fibers are
mitochondiria rich becuase they derive enrgy aerobically. White contract more rapidly but are
easier fatigued.
Sacromeres are made of thick and thin filaments, the thick are mysoin and thin are actin mixed
iwth the proteins troponin and tropomyosin. Z lines are the boundaries of each sacromere. The
M lines run down the center of the sacromere and the Iband is the region exclusively made of
thin filaments while the H zone is exclusively thick filament. I is thinner than H to remember that
the thick is myosin which is also a thicker wrod than actin. The A band is everything but the I
band. During contraction the H zone, the I band and distance between Z lines all become
smaller while A band remains constant. A band is length of actin. Binding of NT like
acteylcholine in the synapse results in contraction of the muscle due to bidning at receptor. The
connection between teh never and muscle is called the nueromuscular junction. This happens
with depolarization of sarcolemma and is the initiation. The action potential generated will be
conducted along the sacroleema and T-system and then transmitted into the muscle fiber. The
sarcoplasmic reticulum is full of Ca2+ and is responsive to depolarizationand prompts release of
Calcium cations, which bind to troponin causing tropomyuosin to shift and exposing myosin
bidning sites on actin. Ca is like a ticket to get by the security the tropomyosin, and exposes the
myosin binding sites on the actin. The globular heads of myosin molecules move towards and
bind exposed sites on actin which draw the thin filaments to the center of the H zone and
shortens the sacromere.
ATPase activity in the mysoin heads provide the energy for th epower stroke and resutls in
dissociation of actin from myosin. The myosin resets itself by binding another ATP.
Relaxation-SR's receptors are no longer stimulated so the calcium levels fall, The product of
ATp hydrolysis that were released from the myosin head during the power stroke leave room for
a new ATP to bind, leading to dissociation of myosin from the thin filament, sacromere returns to
original width and myosin-binding sites are covered by tropomyosin. Rigor mortis arises
because ATP cannot detach actin
Muscle cells work by all or none response based on a threshold value. Muscles control overall
force by the number of fibers they recruit to repsond. Tonus refers to muscles in a constant state
of low level contraction, which is necessary for some muscles.
Simple twitch is the response of a singl fiber, consisting of a latent period, contraction period
and relaxation period. Latent is time between thresholds and onset of contraction. After the
latent period there muscle is unresponsive to stimuli which is known as refractory period, of
which there is absolute or relative. Absolute is when no amount of stimulus will generate a
response while relative the muscle can still be activated but a higher than normal stimulus is
required.
If tehre is to little time for relaxation, the contractions combine and become stronger and more
prolonged, known as frequency summation. When there is know time to relax, it is called
tetanus, if prolonged causes fatigue.
Smooth Muscle is controlled by the autonmic nervous system, and is found in digestive tract,
bladder, uterus, blood vessel walls, and toehr spots. They ahve a single nuclei, have actin and
myoin but not in straited fashion, smooth can contract for longer and without nervous system
input known as myogenic activity.
Cardiac musclesare made of smooth and skeletal muscle, mostly uninucleated, Ca is required in
all contraction of all muscle types. Cardiac also exhibit myogenic activity.
Smooth muscle is good for smooth (continuous contractions) while the rest are for strong
forceful.
Smooth and cardiac are involutary ANS while skeletal is voluntary (SNS) Smooth has 1 nuclei,
cardiac 1-2, and skeletal many. Smooth is also the only non striated.
Muscles can generate ATP from fatty acids, glycogen and glucose as well as high energy
compounds known as creatine phosphate. During times of plenty we storew creatine phosphate
by transphering a phosphate from ATP to creatine, which is reversed during muscle use to
rapidly generate ATP.
As exericisng muscles run out of O2 we use myoglobins reserves to keep aerobic metabolism
going.
Connective Tissue: Loose connective tissue is found throughout the body attaching epithelium
to underlying tissues and holds organs in place. It contains proteinaceous fibers of three types,
collagenous fibers composed of collagine and have great tensile stregth, elastic fibers which are
composed of elastin and endow connective tissue with resilience, and reticular fibers which join
connective tissue to adjoining tissue. There are two major cell types in loose connective tissue,
fibroblasts which secrete substances that are components of extracellular fibers and
macrophages which engulf bacteria and dead cells via phagocytosis.
Dense connective tissue has a higher proportion of collagenous fibers, organized in parallel
bundles giving high tensile strength, and can form tnedons, which attach muscle to bone or
ligamens which hold bones together at joints.
If a given muscle is attached to two bones, contraction will cause only one of the bones to
move. The end of the muscle attached to the stationary bone is the origin, and in limb muscles
corresponds to the proximal end, the other end is the insertion or th in limb muscles the distal
end. Muscles oftne work in antagonistic pairs, one contracts as the other relaxes, bicep and
tricep. The contraction of the antagonistic muscle will lengthen the paired muscel, so if bicep
contracts tricep elongates. Synergistic muscles assist principal muscles during movement.
Flexor decrease the angle of ajoint, while extensors straighten out joint and increase. An
abductor moves a part of the body away fromt eh bodys midline, and an adductor moves
towards.
Review:
Ca2+ binds to troponin which causes strands of tropomyosin to shift exposing myosin biding
sites.
Osteoblasts are involved in secretion of bone matrix, clasts are large multinucleated bone
resorpers, cytes are mature blasts that involve in maintenance,
The epiphyseal plate is the site of longitudinal growth.
Articular cartilage keeps bones from rubbing against one naother.
When mesenchymal cells directly create bone matrix like when ossification occurs in the skull, it
is known as intramembranous ossification.
Adipose tissue is body fat, loosely connected tissue.
Chapter 7
Extracellular Digestion:
Digestion occurs within the lumen of the alimentary canal, This canal is outside of cells and
goes from the mouth to the anus sectioned by sphincters.
Epithelial cells cover our exterior surfaces as well as interior. They are our first line of protection.
They are tightly joined and may be ciliated. The epithelia are known as mucous membranes.
Our skin and epithelial lining prevent fluid lloss by allowing for selective absorption of materials.
It is bound to a connective layer of tissue known as teh basement membrane.
Because of corrosive environment, the epithelium along digestive tract is replaced every few
days.
Epithelial cells can be simply layered meaning one layer, stratified is multiple, and
pseudostratified is when looks like multiple but really one. They can be cuboidal, columnar, and
squamous (scale like as on a snake).
In the mouth there is mechanical and chemical digestion. Mastication is chewing, increasing
surface area to volume ratio allowing for greater gas and nutrient exchange despite no brekaing
of chemical bonds. Hwoever there is enzymatic activity to break chemical bonds. Salivary
glands sevrete saliva which aids mechanical digestion by moistening food, as well as salivary
amylase (ptyalin) and lipase, which hydrolyzes starch into smaller sugars and lipids,
respectively. The tongue than forms the food into bolus before it is swallowed.
The pharynx is the vacity that leads from the mouth and nsoe to the esophagus, it also connects
tot the larynx, part of respiration and the epiglottis folds down and covers the trachea during
swallowing.
The esophagus comes next and connects mouth to stomach, starts as striated muscle and
tranisitions into smooth muscle, so its mostly involuntary. We can initiate a swallow, but the
conintuation of muscle contraction, peristalisis, is involuntary.
As teh bolus apporached the stomach a muscular ring known as the lower esophageal sphincter
opens to allow the passage of food.
The mucosa lining the stomach is thick to rpotect from autodigestion. The mucosa contain
gastric glands and pyloric glands. The gastric respond to signals from the brain, activated by
sensing food, and they consist of mucous, chief, and parietal cells. mucous cells produce mucus
b/c pH of 2 and proteolytic environment.
Gastric juice is a product of the cheif and parietal cells. The chief secrete pepsinogen which is
the zymogen form of the prteolytic enzyme pepsin. pepsin will digest proteins by cleaving
peptide bonds near aromatic amino acids. Parietal cells secrete HCl. The zymogens must be
activated by HCl, so pepsin in unique in that it is most active at pH 2. The acid also kills most
harmful bacteria, with the exception of helicobacter pylori which causes ulcers.
The pyloric glands secrete gastrin, a hormone, which induces our stomach to secrete more HCl
and produce an acidic semifluid mixture known as chyme, which is passed to the small
intenstine. Certain substances like alcohol and aspirin can be absorbed in the stomach but it is
primarily a digestive site. Food leaves the stomach through the pyloric sphincter entering the
duodenum of the small intestine. SI is 6 meters long. the surface of the SI is covered in villi each
of which has a set of microvilli, increasing the surface area dramatically. Bacteria line the
duodenum. Most digestion in the duodenum, and accessory organs like liver gall bladder and
pancreas are important. Chyme triggers teh release of hormones that leads to secretions from
SI and accesory organs.
Pancreatic juice is a complex mixture of several enzymes in a bicarbonate solution important for
neutralization of acidic chyme. Enzymes produced by the pancrease are most active at pH of
8.5, the enzymes can break down all three types of nutrients. Pancratic amylase breaks down
large polysaccharides into small disaccharides (carbs). Pancreatic peptidases (trypsinogen,
chymotrypsinogen, eslatinogen, and carboxypeptidase) are released in their zymogen form and
are responsbile for protein digestion. Enterokinase, produced by teh small intestine is the
master switch, activating trypsinogen to trypsin, which actiaves the other zymogens. The
pancrease also secretes lipase which breaks down fasts to free fatty acids.
Bile is acomplex lfuid made up of bile salts, pigments and cholesterol, produced by the liver and
stored in gall bladder, which releases it into the duodenum by way of the bile duct, in repsonse
to the hormone CCK, chloecytoskinin, which is released by SI in response to movement of
chyme from stomach to SI. Bile has pH between 7.5 and 8.8 to similarly neutralize the chyme.
Bile salts made from cholesterol are not enzymes so do not cleavage enzymatically but have an
important emchanical role which facilitates digestion of lipids. Like phospholipids bile salts have
a hydropho and hydrophil region. They allow fats to be emulsified, because chyme is aqueous
without bile fats would seperate out of the mixture, instead the cholesterol mixes and forms
micelles, which also expose more of the surface of fats to actions of lipase, so we need bile and
lipaseto work together. Lipase hydrolysed those ester bonds.
Chyme in the duodenum causes SI to release disaccharidases such as maltase, lactase and
sucrase, peptidases, including dipeptidiases inlcuding enterokinase secretin and CCK.
Peptidases break down proteins, Secretin is a hormone that causes pancreatic juice to be
exuded by the pancrease and CCK stimulates the release of pancreatic juice and bile.
If we had a very fatty meal the duodenum releases teh hormone enterogastrone to slow the
movement of chyme allowing more tiem to digest fat. When digesting feel tired because of
parasympathetic versus sympathetic divistion of digest or fight or flight, respecitvely. Absorptive
functions mostly occur in teh jejunum and ileum. sugars and AA are absorbed by active
transport and facilitated diffusion. into the epithelial cells lining the gut. Move across to the
intestinal capillaries, and blood carries them away following concentration gradients, blood has
lowest concentration, absorbed molecules then go tot he liver via teh hepatic portal circulation.
Most fat bypasses the liver.
Small fatty acids follow same process as carbs and AA difusing into intestinal cappilaries and
dont need transporters becuase they are nonpolar, easily traversing celluar membrane, larger
fats, glycerol and cholesterol move seperately but reform. Teh triglycerides are packaged into
chylomicrons and ratehr then enetering lboodstream endter lymphatic ciruclation through
lacteals, small vessls that form the begining of the lymphatic system. The lacteals converge and
ente the venous circulation throug the lymphatic duct in the neck region.
Chylomicrons are processed directly in the bloodstream into low density lipoproteins, bad
cholesterol, and can lead to atherosclerosis. Ldl moelcules can be taken up by the liver and
turned into HDL H for healthy.
Vitamins ADEK are fat soluble adn the rest are water soluble. Failure to absorb fat would cause
failure to absorb vitamins but water soluble are absorbed with water, AA and carbs across the
endothelial cells and pass directly into plasma.
The large intestine is involved in water absorbtion and salts (thereby controlling constapation
and diarrhea), and has a larger diamter but is only 1.5 m long. The large is divided into cecum,
colon, and rectum, Cecum is a pocket with no outlets that connects the SI and LI and contains
the appendix, which wards off bacterial infections. The colon absorbs water and salts and is a
last chance to absrob nutrients.
The rectum stores the feces, which is indigestible waste like water, bacteria.
The anus is the opening through which wastes are eliminated, and consists of two sphincters
the internal and external. The external is voluntary (somatic) but internal is autonomic. In
dueterostomes the blastopore gives rise to the anus.
Review:
Chief cells secrete pepsionegen, the zymogen of the protein hydrolyzing enzyme.
Enterokinase activates trypsinogen to turn to trypsin, which activates caroxypeptidase,
chymotrypsin is the active form of chymotrypsinogen, also activated by enterokinase.
Proteins are digested in stomach and SI
pepsin works at low pH
Food should not go to trachea
chylomicrons go through lacteals
Chapter 8:
Air enters the external nares of the nose, which will then filter with cilia, pass through pharynx
and larynx. From the lar it passes into the trachea and then to two bronchi, which split into
broncholes and then alveoli. The bronchi and trachea also contain ciliated epithelial cells to
filter, each alveolus is coated with surfactant, that lowers surface tension and prevents alveolus
from collapsing on itself. Ther eis anetwork of ccapillaries for gas exchange. Lots of surface
area.
The lungs are contained in teh thoracic cavity, which also contains the heart. and are seperated
from digestion by the diaphragm. Inspiration is a term for drawing air into the lungs.
Skeletal muscle lines the diaphragm despite breathing being automatic.
The cehst wall is the boundary of one side of the thoracic cavity. Pleurae surround each lung,
and are a closed sac. It is composed of the visceral, whcih toughes the lung and the parietal
pleura. The space between is called the intrapleural space, which contains a thin layer of fluid.
There is a pressure differential beteen the intrapleural space and the lungs, which is important.
During inhalation we use our diaphram as well as external intercostal muscles, which are
between the ribs to expand the thoracic cavity, this decreases pressure in the intrapleural space,
but the gas in the lungs is at atmpospheric pressure which is higher. As teh lungs take in air
they expand, which is called negative pressure breathing because the driving force is the lower,
pressure in the intreeapleurla space.
Exhalation occurs as diaphram and external intercostals muscles relax, the chest cavity
decreases and pressure in intrapleural space increases, so air will be pushed out of lungs.
When exericising we also use internal intercostal muscles, which oppose the externals.
Ventilation is primarily regulated by enurons, ventilation centers in teh medulla oblongata,
sensitive to CO2 levels and increase respriration with increased CO2. Chemoreceptors on the
neurons surface monitor blood pH, I believe as pH goes up that means more CO2 because of
lechatelier more H2Co3, which is an acid.
We can control breathing but if we hyperventillate of hypoventilate the medula takes over.
The spirometer is used to measure amount of air normally present in lungs and rate of
ventillation. Normal respiration is 12/min but higher up less O2 nead more breaths.
Total lung capacity for a healthy human is 6-7 L. IF we breathed out until entirely, the total
amount we force out was the vital capcity. The amount left over is the residual volume. Expelling
all the ari would cause lung collapse, So the residual volume pluis vital capacity =TLC.
However we mostly breath in less, the ttidal volume, and the this si also the same amount that is
exhaled in normal breathing. If we use respriratory msucles the last bit of air that gets pushed
out is the expiratory reserve volume. The inspiratory reserve volume is the amount of extra air
we can take in. THe TV+ the ERV and IRV=the Vital capacity, whcih is the total amount of gas
that can be moved.
The capilaries bring deoxygenated flood from pulmonary arteris from the righ ventricle, as they
apporach the single celled alveolar layers allow for diffusion of co2 from blood into lungs and O2
the opposite way. and the O blood returns via pulmonary veins. The driving force is the pressure
differnetial of the gases through a concentration gradient, so no energy is needed. Hemo is
always used to transport the O2
When O2 shortage we can also make more red cells to carry the O2 instead of jsut breathing
more, or even more blood vessles, which would facilitate the dsitribution of a lwoer amount f O
or we could alter the bidning dynamics of hemo.
Review:
Thin and moist alveolar surfaces faciliatate gas exchange
Negative pressure breathing refers to inhalation
To prevent the lungs from collapsing we have the pleurae surrounding and protecting the lungs,
and the surfactnat reduces sufrace tension preventing colapse.
The epiglottis coers the glottis to ensure that food does not enter the trachea during swallowing,
pharynx->larynx->trachea->bronchi->alveoli
Exhalation and gas exchange but not inhalation are passive processes.
Chapter 9:
The cardiovascular system consists of the heart, blood vessels, and blood. The heart is two
punps connected in series, the right pump accepts deoxygenated blood from the body and
moves it to the lungs by the pulmonary areteries, the left pump receives o blood from lungs by
pulmonary veins and forces it to the body through the aorta.
Each side of the heart is made of an atrium and a ventricle, teh atria are thin walled, and then
pass it to the ventricle which is muscular and work as the pump. The aorta is the largest artery,
and breaks into important arteries like the coronary, commor carotid, and renal, which then
break into arterioles and ultimately capillaries. on the venous side of the capillary network the
cappilaries join together to form venules and then veins, ultimately to the inferior or superior
vena cava. Sometimes blood passes through 2 cappilary beds, connected by venules before
returning, and these are portal systems, such as hepatic portal which goes from intestines to
liver and hyophyseal portal system which goes from they hypothalamus to the pituitary gland.
The heart is located between the lungs, and cardiac muscle is the only type of muscle in the
heart.
The left side must be more muscular. the total volume of blood is about 5 liters/ minute.
Valves- the heart moves blood throug the vasculate by generating pressure through contraction.
Different valves ensure the blood flows in one direction, between the atria and ventricles we
have the atrioventricular valves, the right AV valve is caleld the tricuspid valve, because it has 3
leaflets, the left has only two and is the bi cupsid or mitral valve.
Each ventricle is protected from backflow by the semilunar valve. the right is called the
pulmonary valve, and the left is the aortic valve. AV valves prevent backflow durign contraction
(systole), while ventricle valves prevent backflow during relaxation, (diastole).
cardiac output is the amount of blood volume pumped per minute. It is the product of heart rate
and stroke volume (volum eof blood pumped per beat.
Cardiac muscle like smooth muscle demonstartes myogenic activity, so heart can beat without
brain or with autonomc nervous system regulation.
Each heatbeat is composed of systole, ventricular contraction and closure of AV valve and
disatole where heart is relaxed and semilunar valves are closed. If the walls of arteries were not
elastic teh diastolic blood pressure, which is the gauge pressure would plummet to zero and we
would die.
The coordinated contractions of the cardiac muscles originates inan electrical impulse through
four excitable structure,s the sinoatrial node, the atrioventricular node, the bnundle of His (AV
bundle) and the purkinje fibers. Initiation begins at the SA node, located in the wall of the right
atrium, depolarization spreads causing two atria to contract simultaneously, the systole causing
an increase in atrial pressure pumping blood into the ventricles. next the signla reaches the AV
node between the atria and ventricles and can be delayed so the ventricles fill, then travels
down teh bund of his embedded in the interventricular septum, and to the purkinje fibers which
distrubte the electrical sginal through the ventricular muscle causing ventricular contraction.
The double sound of the heart is acutally teh valves closing and so the pumping happens at the
same time in each half of the heart.
The SA node adn human heart rate is 60-100 signals per minute. The autonomic division which
consists of parasympathetic and sympathetic which controls rest veruss flight, controsl the
heart. para slow the heart via the vagus nerve, while sympathetic speed it up.
Arteries are are strong, thick walled structures that carry blood away from the heart. Veins are
thin walled nad inelastic and transport blood to the heart. The exception of O are pullmonary
and umbilical vasculature. The same cells comprise arteries and veins. Arteries have more
smooth muscle than veins. Arteries over high resistance because of elasticity, this elasticity
recoils and ensure blood continues forward. Veins are capacitive and can carry large amounts
of blood and actually contian more blood at any point in time then arteries. Pressure at bottom
of veins is high, so how do they prevent backflow. Larger veins have one way valves to prevent
backflow. blood flowing forward pushes valves open, but closes when moves backwards.
Failure leads to vericose veins. pregnant women are susceptible becasue of added blood
volume. Also most large bveins are surrounded by skeletal muscle which squeezes the veins as
muscles contract forcing the blood up against gravity, this is why sitting otionless for logn
periods of time can increase risk of pulmonary embolism. So a clot could form in a vein adn then
spread and get stuck in smaller vein.
Capillaries are vessels with a single endothelial cell layer that makes exchange easier, often
blood cells go by in single file.
Blood pressure, is based on pressure gradient, and is measured in force per unit area exerted
on the wall of blood vessels. A sphygmomanometer measures gauge pressure in the systemic
circulation, recorded as a ratio of systolic to diastolic pressrues. The largest drop is across
areteriorels because need low pressure for caps but continues to fall through veins to vena
cava.
Using a centrifuge we see that blood is composed of 55% liquid, 45% cells, Plasma is the liquid
portion and is an aqueous mixture of nutrients, salts, respiratory gases, hormones and blood
proteins. The cells are made up of erthrocytes, leukocytes and platelets. They are all formed
from hematopoietic stem cells, which originate in the bone marrow.
Erthroctes are specialized for O2 transport. Each contians 250 milliom hemoglobin porteins and
each can bind four moelcules of O2, On the surface they have a biconcave disk shapethat
serves a dual purpose, assisting in travelling through tiny capillaries and increasing SA. As they
mature, they lose their nucleus, mitochondria and other memranous organelles, clearing room.
This means rely on fermentation and cannot divide. Cells in the spleen and liver phagocytize
them for recycled parts after 120 days.
Leukocytes (White blood cells) form in marrow, only 1% of blood volume except during infection
because important for immune system. There are 5 different types categorized as granulocytes
or agranulocytes.
Granular leukocytes include neutrophils, eosinophils and basophils and act as bombs containing
toxic compounds for invading microbes.
The agraulocytes do not contain granules consist of lymphocytes and monocytes. Lymphocytes
are important for specific immune responses, to viruses and bacteria by fighting an infection and
maintaining a memory bank.
Lymphocytes can mature in the spleen or lymph nodes and a referred to as B-Cells, if they
matured in teh thymus they are T cells. B cells are responsible for antibody generation while T
cells kill virally infected cells and activate other immune cells.
Monocytes phagocytize foreign matter like bacteria and are named macrophages once they
leave the marrow. In the brain they are called microglia.
Platelets are cell fragments derived from the breakup of cells known as megakaryocytes in the
marrow. They clot blood.
A direct way to identify a cell type is to examine proteins expressed on the extracellular surface
of the cell membrane. These proteins are referred to as antigens. For blood cells their are the
ABO antigens and the Rh factor protein.
If one is a blood type A the antigen is A and produce anti-B anti-bodies.
AM makes no antibodies and O makes anti a and b
A and B are co-dominant. O is recessive to both.
The Rh factor is a surface protein expressed on red blood cells and one predominant variant
indicated by + or -. Rh+ indicates the individual express the Rh protein and + is dominant.
During child-birth women are often exposed to fetal blood and if a woman is - and her fetus is +
she will become sensitized and her immune system will make antibodies, for subsequent
pregnancy , maternal anti Rh antibodies can cross the placenta and attack fetal blood cells,
resulting in hemolysis of fetal cells, erthroblastosis fetalis, wchih can be fatal. ABO do not cross
placenta though.
Actual binding of O2 on hemo is by the Fe atom which can maintain different oxidation states.
As first O binds to a heme group it induces a conformational shift from taut to relaxed, and
increases affinity for O, once full removal of O results in conformational shift, COOPerative
BINDING and the graph has a sigmoidal shape, it is an allosteric effect.
CO2 can be carried by hemo but generally exists as bicarbonate, When Co2 enters a red blood
cell it encounters carbonic anhydrase, catalysing combination fo water and Co2, it will lose a
proton. Once blood reaches caalveolar caps the process is reversed. pH of blood has effects on
hemoglobin. Increased proton concentration shifts the curve to the right, meaing we have less
saturation of Hb, known as teh Bohr Effect, which will be when we have high energy demands
like running a race. We also require more O2 because of cellular metabolism, which yields more
Co2 and accumulation of lactic acid, both of which decreases pH signaling to the hemo that the
tissues need more O2. So hemo will experience reduced affinity for O2and we will be able to
give off or dump more O2 to metabolically active tissue, because its a down right shame not to
have enough O2 to finish teh race. So the allosteric effect of protons is shifting curve to the right
meanign lower affinity.
pH of blood is 7.4 miantained by carbonic buffer. If there is acidosis the respiratory rate wil
licnrease to reduce the systemic PCO2.
Once in the blood stream fats are packaged in lipoproteins which are water soluble.
CO2, ammonia, and urea enter the bloodstream throughout the body as they travel down
concentration gradient from tissues into capillaries. Blood passes through excreatory organs
where waste is fitlered or secreted fro removal.
In blood we have pressure gradient related to fluid volume and solute concentration. They are
controlled by hydrostatic and oncotic (osmotic) pressures. Hydrostatic is generated by
contraction fo the heart and elasticity of the arteries. Capillaries are leaky so fluid will be forced
out of blood stream into inrstitial space. By teh veins the hydrostatic pressure drops below
oncotic pressure, which is the pressure generated by teh concentration of particles and in
capilaries nutrients filter out and wastes in at a relatively equal rate. Oncotc pressure exerts an
inward force and drwas fluid nutrients and wastes out of the tissue and into the stream. The
balance of the forces is called the starling fong forces, and is important for proper
concentrations. Too much fluid in interstitum is called edema, and is taken up by lymphatic
system, which is another circulatory system and eventually returns to central circulatlory system
by way of a channel called the thoracic duct.
Platelets protect the vascualr system in teh event of damage to a vessel by forming a clot,
preventing loss of blood. Connective tissue is partially composed of collagen, and platelets
come in contact they sense this as evidence of injury, release content and gein aggregating, and
release a clotting factor known as thromboplastin, which converts prothromin into thromibn with
some hlep from cofactors like Ca and vitamin K. Thrmobin converts fibrinogen into fibrin which
makes fibers that aggregate into a net capturing red blood cells and paltelets forming a clot.
Hemophilia causes malfunction in the cascade.
Review:
Hemoglobin affinity for O2 decreases as blood pH decreases
Mature erthrocytes have no nuclei
O- if we dont know someones blood and they need a transfusion.
The relative lack of smooth muscles in venous walls allows stretching to store most of the blood
in the body
Osmotic pressure of surroudning tissues is contanst but hydrostatic pressure at the arterial end
is greater than at the venous end, so fludi movs out at teh arterial end and back in at the venous
end
Chapter 10
Leukocytes which are vital for specific immunity are made in the marrow and contribute to innate
(general) or adaptive (specific) immunity. Granulocytes include neutrophhils, eosinophils, and
basophils. Agranulocytes include lymphocytes (antibdoy production, immune system modulation
and targeted killing of infected cells) split into B cells and T cells (mature in spleen and thalamus
respectively), while monocytes (primarily macrophages nonspecific sanitation workers that travel
the body picking up debris of invaders and doemstic. The specific immune system can be
broken down into teh humoral immunity driven by B cells and antibodies and cell mediated
immunity provided by T cells.
Antigens allow immune system to distinguish us from them. The immune can learn to
specifically recognize some antigens. Autoimmunity is when body attacks itself. Allergies is
when the body identifies a harmless particle like peanuts as threatening causing hypersensitive
reactions.
Nonsepcific Defense: skin or integument is the first defense, sweat contains an enzyme that
attacks bacterial cell walls. Next we have mucous membranes lining respiratory passages to
trap particulate matter and push it up towards the oropharynx, so it can be swallowed rather
than reach the lungs. tears and saliva also contain lysozyme to destroy bacteria. When foreign
particles do make it past, macrophages phagocytize them. They come to sites of inflammation
by chemicals such as histamine which cause vasodilation (widening of blood vessels) to allow
movement from blood stream to tissue. Granulocytes, especially neutrophils may be called out
in a similar manner. This works well against pathogens that are extracellular like bacteria.
Cells infected with viral particles produce interferon, a protein that prevents viral replication and
dispersion. However, these systems are not adaptive.
The adaptive immune system forms an immunological memory.
Adaptive immune takes time, The humoral immunity which involves production of antibodies
may take a week but are specific to the antigens of invading microbe. Antibodies are produced
by B-Cells. Antibodies which are also called immunoglobulins bind to antigens, attract other
leukocytes to phagocytize, or clump together to form large insoluble complexes that can be
phagocytized. Antibodies are y shaped molecules that are made of two identical heavy chains
and 2 light chains, Disulfide linkages and noncovlaent interactiosn hold the chains together.
Each has an antigen bidning region at the top tips of theY and have specific pollypetide
sequences that will bidn one specific anigenic sequence. Each B cell makes on antibody but we
have many B cells so the immune system can recognize many antigens. The rest of the
antibody si the constant regiona nd is invovled in recruitment and binding to toher immune
modulators like macrophages.
B cells wait in lymph nodes for particular antigens to come along. Upon exposure B celsl makes
two daughter cells, Plasma cells which produce large amounts of anti bodies and memory cells
which stay in lymph nodes, for re-exposure. This takes 7-10 days and is the primary response.
Plasma cells die but memory last a life time.
If the same microbe is ever encountered again the memory cell jumps into action producign
anitobdies which is fast and large called the secondary response. This is the basis for vaccines.
Cell mediated immunity like humoral immunity is a sub section of specific immune response but
uses the T-lymphocytes, also originally from bone marrow, but these mature in thymus. There
are three types. help T, supressor T and killer (cytoxic T cells. Helper aka T4 express the CD4
cell surface protein, coordinat the immune response by secreting chemicals known as
lymphokines. They recruit other immune cells like plasma cells, killer T and macrophages.. The
loss of these cells impairs the immune response to infection. HIV destroys T4 cells. Cytotoxic T
cells aka T8 express the CD8 surface protein and directly kill virally infected cells by secreting
toxic chemicals. Supressor T are another group of T8 cells, which help tone down immune
response once infection is contained.
T cells also form memory cells so the next exposure will be more efficient.
Autoimmunity and when liver donor use immunosuppressants.
Immunization can be achieved in an active or passive fashion.
Active immunity can be achieved through natural or artificial exposure either way the B cells are
activated and mkae memory cells.
Passive immunity is when antibodies are transfered, such as transfer across the placenta. An
artificial method is to give a drug to an Rh- woman to prevent sensitization to the Rh+ fetus
blood.
The vaccines also make T cell memory.
Note T cells mature in thymus which is near the lungs not thalamus.
The lymphatic system is a type of circulatory system with one way vessels that become larger
as they move towards the center of the body. The vessels carry lymphatic fluid and join to
comprise a large thoracic duct in the chestExcess fluid not reabsorbed in interstitial space is
colelcted by lymphatic vessels and returned to cardiovascular circulation. The smallest lymph
vessels, lacteals, collect fats in the form of chylomicrons from teh villi of the small itnestine and
eliver them to the bloodstream. Swelling in the vessels are lymph nodes contianing B cells, like
security check points.
Active immunity requires weeks to build and is long lived, while passive is short lived because
antibodies in circulation but once born gone.
Chapter 11
The functional unit of the kidney is the nephron. Each kidney is divided into the cortex on the
periphery and the medulla medial. Then there is the renal pelvis which is even more medial and
the renal artery, vein and ureter enter and exit the pelvis. The renal artery branches out through
the medulla and intot he cortex as afferent arterioles. The capillaries that emerge are called
glomeruli, and form a highly convuluted structure. After blood passes through the glomerulus
the efferent arterioles lead the blood away. So its not that they lead to venules. The arterioles
then lead to a second set of capillaries known as the vasa recta.
The clompex net of capillaries is surrounded by a cuplike structure known as bowmans capsule,
which leads to a long tubule with many distinct areas, leading to the proximal convoluted tubule,
descending and ascending limbs of the loop of henle and the distal convoluted tubule and finally
the collecting duct.
Filtration-20% of blood that passes through the glomerulus is filtered into bowmans space. The
collected fluid is known as the filtrate and lacks cells or proteins due to the filters selection
based on size. So molecules biger than glomerular pores remain in the blood. Then the the
blood goes throughe fferent arterioles to the vasa recta. The filtrate is isotonic.
Secretion-nephrons also secrete salts, acids, bases, and urea into the tubule by active and
passive transport as well as remove other substances present in excess in teh blood. Secretion
also works for excreting waste too large for glomerular pores.
Finally the nephron can also perform reaabsorption of amino acids and lgucose so as not to
throw out the goods.
So the nephron starts at the glomerulus and bowmans capsule and continues through tubules.
Proximal and distal tubules reabsorb many substances including water. The ascending and
descending limps are more selective. The descending limb is permable to water but not salt,
while ascending is permeable to salt but not water. The collecting duct almost always reabosrbs
water but hte amount is variable. When teh body is well hydrated, the collecting duct will be
fairly imperable to salt and water, in conservation mode, antidiuretic hormone and aldesterone
will act to increase permeability of the collecting duct allowing for greater reabsorption and more
concentrated urine output.
The kidney can alter the osmolarity of the interstitum, allowing for reabsorbing or excreting
different compounds. Together they work as a countercurrent multiplier system. Normally, the
osmolarity of the cortex is the same as blood. The medulla interstitum can be isotonic with
blood, to four times moure concentrated, when trying to conserve water, b/c water moves out of
tubule into interstitum and back into blood
In proximal convoluted tubule, glucose, AA, soluble vitmans and majority of salts are
reabsorbed along with water but the filtrate remains isotonic to the intersittum. Protons are the
only thing that enter. In the descending limb of the loop of henley only water is permeable and
the concentration of interstitum rises to water is pushed out. The ascending limb is permeable
only to salt and as moves up concnetration of external decreases and alt will be pumped out of
the limb. The distal convoluted tubule maintains the same concentration as the cortex by
reabosrbign salt and water in equal proportions. The final concentration depends on the
permeability of the collecting duct. As perm increases so does water removal, which is
controlled by the antiduretic hormone ADH and aldosterone.
Aldosterone is secreted by the adrenal cortex in response to decreased blood volume, which
causes low blood pressure (hypotension). Aldosterone is released in response to an increase in
angiotensin which is regulated by renin.
Aldosterone works by altering the collecting ducts ability to reabsorb more sodium, which means
water will follow it out, increasing lbood volume and blood pressure. Aldo also increases K
excretion. For people with high blood pressure, we give them a durg that blocks aldosterones
receptor, so less sodium and water are reabsorbed.
ADH aka vasopressin is a peptide hormone that directly alters permeability of the collecting duct
cells, allowing more water to be reabsorbed by making the cell junctions leaky, increasing
concentration in the interstitum, which causes reuptake of water from the tubule. ADH is made
in the hypothalamus, and kept in the posterior pituitary, and secreted when blood osmolarity is
high, alcohol and caffeing inhibit adh leading to dilute urine. (ADH and aldo both icnrease
concentration one through salt and the other though water).
After collecting duct there are no further transporters or reuptakes. Filtrate is collected in teh
renal pelvis, consisting mostly of urea, uric acid, and excess ions, and flows through the ureter
to the bladder where it is stored till voiding. IT is excrete through the urethra. There should
never be blood, protein or glucose in urine.
The liver also helps with blood glucose regulation and elimination o fnitrogen waste through
urea. Nutrients absorbed during digestion are delivered tothe liver through the hapatic portal
vein. The liver transforms glucose into glycogen when excess. During famine, glycogen is
broken down. The liver also can make new glucose from other precursors through
gluconeogensis.
Proteins are composed of amino acids contianing amino groups. Amino acids can be used for
cellular respiration, but first they must undergo deamination, which leaves toxic ammonia, but
hte liver combines it with carbon dioxide to create urea.
The liver is also involved in detoxification, storage of vitamins, destruction of old erythrocytes,
sythensis of bile and blood proteins, efense against antigens, beta oxidation of fatty acits to
ketones, and gluconeogensis.
The large intestine is also capable of reabsorbing salt and water but not directing overall fluid
balance.
The skin is the largest organ and is made up of layers, epidermis, dermis and hypodermis. Skin
comes frome ctodermal germ layer. The epidermis is divided into the startum corneum, stratum
lucidum, stratum granulosum, stratum spionsul and startum basalis in order from exterior to
interior.
The outer layers are formed from cells that have pushe dup from teh startum basalis. At the
outeermost layer they die and lose their culei forming scales of keratin. Hair projects out and are
openings for sweat glands.
The ermis also has multiple layers including the papilalry, followed by the reticular layers. The
sweat glands, sense organs, blood vessels and hair follicles are in dermis.
The hypodermis is the layer of connective tissue that connects our skin to our bodies.
The skin portects from UV light, and allows for thermoregulation in endotherms, maintain a
constant temp aka homeotherms rather than ectotherms.
Melanocytes are epidermal cells that secrete melanin, which keep us safe from UV.
Thermoregulation is also achieved by vasodilation and vasocontriction.
HEat loss is prevented by fat insulation as well as hair.
Long period of decreased arousal, torpor, when warm aestivate, and cold hibernation,
metabolic, heart and respiration are slowed.
Review:
Platelets and most proteins are filtered by the glomerulus.
Sodium is actively transported out of every part of nephron excep loop of henly where its
passive. Water is always passive. Chloride ions are always passive. Protons and Potassium are
always active. Based on negative inside and positive outside other than amino acids and
glucose which are active. Also anything entering other than urea is active.
ADH acts on the collecting duct not proximal tubule.
In the nephron AA, glucose, salts and water enter the vasa recta via reabosrption.
The hypothalmus functions as a thermostat regulating temperature.
Bile is produced in liver but not stored.
To think about tonicity think in terms of cell placed in a hypertonic or hypotonic solution, hypo
means it will explode. So hypotonic to something means it has a lower concentration
Chapter 12
Autocrine is when signalling takes place within the cell, paracrine is when a nearby cell and
endocrine is when its far. Different hormones are involved in the signaling.
Many organs of endocrine capabilities including the hypothalamus, pituitary, testes, ovaries,
pineal gland, kidneys, gastroinestinal glands, heart and thymus. Each can synthesize and
secrete a hormone. Hormones can be peptides or steroids and must be able to bind to
receptors. So hormones are controleld by release and presence of receptors on target organs.
The hypothalamus is the master control gland in teh brain. It regulates the pituitary. The
hypothalamus is connected to the pituitary via the hypophyseal portal system (hypo means
below) where hormones are rleased by hypothalamus and travel to the anterior pituitary and
stimulate the relase of others.
The gonadotropin-releasing hormone (from hypothal) causes the anterior pituitary to release
follicle stimulating hormone and luteinizing hormone.
The growth hormon releasing hormone causes the release of the growth hormone.
The prolactin inhibitory factor releases prolactin
The thyroid releasing hormone releases thyroid stimulating hormone
The corticotropin rleasing hormone releases adrenocorticotropic hormone.
For each the increase of relase from Hthal causes increase release from pituitary except the
PIF/prolactin relationship where prolactin is inhibited by prolactin inhibitory factor.
The Hthal always has releasing in it and a similar name while the pituitary hormones often have
stimulating.
Excessive levels are dangerous os there is always feedback inhibition. For example with the
corticotropin releasing factor, it increases adrenocorticotropic hormone which goes to adrenal
and causes increase in cortisol but the hthal and pituitary have receptors for cortisol for negative
feedback.
Oxytocin and ADh are made by Hthal but stored in posterior pituitary which is activated not by
hormones but by axons.
The anterior pituitary can be caterogized by direct or tropic roles. Direct hormones bind to
receptors on the target organs and act directly. Tropic hormones bind to receptors on an organ
and cause the relase of effector hormones
Direct Hormones:
PEG- growth hormones work by preventing lgucose uptake in certain non growing tissue and
stimulating breakdown of fatty acids, increasing glucose levels which are necessary for the bone
and muscle growth.
Growth Hormones are of course tied to GHRH.
Growth in bones occurs at epiphyseal plates, which seal at puberty. An excess or defecit of GH
in childhood results in gigantism or dwarfism. GH can effect adults, particularly smaller bones,
and if in excess its called acromegaly.
Prolactin is important in females and stimulates milk production in mammary glands. Milk prod in
males is bad.
Endorphins modulate pain and morphine mimics it.
Tropic Hormones act indirectly and ACTH is reuglated by CRF and induce the release of
glucocorticoids, which affect sugar balance in the body. TSH controleld by TRH stimualtes the
thyorid to take up iodine and release thyroid hormone. LH and FSH controlled by BnRH affect
the ovaries and testes.
For posterior Pituitary ADH and oxytocin. Oxy is secreted during childbirth to coordinate
contractions of uterine smooth muscle, and can be secreted as ar esult of suckling which lead to
mulk production.
ADH works with colelcting duct making it more permeable to water based onl ow blood volume
detected by baroreceptors or by osmoreceptors which are sensitive to osmolarity.
The thyroid is controlled by TSH and has two functions, setting basal metabolic rate and calcium
homeostasis. It controls basal metabolic rate by releasing thyroxine and triiodothyronine.
Calcium levels are controlled by calcitonin.
THyroxine (T4) and triiodothyronine (T3) are produced by iodination of the amino acid tyrosine
in the follicular cells of the thyroid. 3 vs 4 refer to number of iodine. THe thyroid hormones make
energy production more or less efficient, as well as altering utilization of glucose and fatty acids.
Increased amounts of T3 and 4 lead to increased cellular respiration. High plasma levels of
thyroid hormones cause decrease in TSH and TRH synthesis as neg feedback system.
A deficiency in idoine or inflammation of thyroid can cause hypothyroidism, where not enough
thyroid hormones secreted, causing lethargy, decreased body temp and slower respiration adn
heart rate, as wella s weight gain. In children low levels cause mentral retardation and cretinism
(developmental decay).
Hyperthyroidism is the exact opposite. In either condition the actual thyroid may enlarge, known
as goiter.
Follicular cells build thryoid hormones and C cells produce calctonin, and decrease palsma
calcium levels by increasing exretion from kideys, decreasing absbrtion in gut, and increasing
storage in bones.
The parathyroid gland makes the parathyroid hromone, and is antagonistic to calcitonin,
increasing plasma levels of calcium by reversing the effects of calcitonin (tones down), including
causing bone resorption (removing Ca from bone)
PTH also activatess Vitamin D to its active form, which is required for absorbtion of Ca in teh
gut. ANd as levels of plasm aCA rise PTH secretion is decreased.
Adrenal glands are atop the kidneys, and consist of cortex and medulla. The cortex secretes
corticosteroids, in response to ACTH stimulation, all corticosteroids are steroid hormones
meaning they are derived from cholesterol, and are divided into glucocorticoids,
mineralcorticoids and cortical sex hormones. The three S;s sugar slat and sex.
The two glucocorticoid sare cortisol and cortisone, they incresae gluconeogenesis and decrease
protein synthesis. They also decrease iflammation and immunological responses. It is also
released in response to stress.
Mineralcorticoids-control salt balance through kidneys. Aldosterone is an example-leading to
higher blood pressure. It can also enhance secretion of hydrogen ions and potassium ions by
making them more permeable to the tubule. aldosterone is controled by the
renin-angiotensin-aldosterone sytem. Decreasing blodo volume causes the juxtaglomerular cells
of the kidney to secrete rening, which cleaves an inactive plasma protein, angiotensiongen to its
active form, which converts to angiotensin II, whch stimualtes the adrenal cortex to secrete
aldosterone. Once fluid volume is restored, negative feedback and no renin is released.
The adrenal also makes male sex hormones (androgens) but since in maels more made in
testes not important as in females. Too much has masculainizing effects.
In the adrenal medulla (derivative of nerbous system) flight of flight hormones are controlled by
epinephrine and norepinepherine, and secrete them directly into the circulatory system, which
are peptide hormones that are part of catecholamines. They decrease digestion, epinephrine
increases convesion of glycogen back to glucose in liver and muscle as well as increasing the
basal metabolic rate. Both compounds increase heart and repsitarotry rate, and increase blood
flow by vasodialtion leading specifically to skeletal msucle heart lungs and brain. and vaso
constriction to guts kidney and skin.
Pancreas: (endocrine to blood stream exocrine to external environment) The islets of
langerhans is very important, there are three types of cells, alpha beta and delta. The alpha
secrete glucagon, beta insulin and delta somatostatin.
Glucagon is a hormone that is antagonistic to insulin, and is secreted during famine, stiulating
degradtion of protein and fat conversion of glycogen to glucose. Also gastrointestinal hormones
like CCK and gastrin increse glucagon release. During feasts it is inhibitted.
Insulin induces muscle and liver cells to take up glucose and store it, and stimulates anabolic
process such as fat and protein synthesis. In excess insulin causes hypoglycemia, low blood
glucose, insensitivity to insulin or insufficicent secretion result in diabetes mellitus, characterized
by hyperglycemia. Exccess with result in presence in urine. and exccess excretion of water, so
diabets often reporty polyuria, incresaed urination and polydipsia, increased thirst. Typie I is
caused by autoimmune destruction of beta cells, so inject insulin, Tpe II body resisting effects of
insulin Drugs and diet can control. Its important to keep in mind that growth hormone and
glucocorticoids and epinehphrine are also capable of icnreasing plasma glucose.
Somatostatin is an inhibitor of insulin and glucaon, stimualted when high glood glucose and
amio acid concentrations.
Testes: spermatogensis requires interplay of FSH and LH. FSH stimualtes the sertoli cells and is
necessary for sperm maturation, while LH causes the intersitital cells to produce testosterone,
the major androgen, important for spermatogensis, and for male embryonic differentiation,
development at puberty, and maintenance of secondary sex characteristicsts, like pubic hair. It
also provides negative feedback to GnRH, If receptros for testoseterone dont work, the result is
andogen insensitivty syndrome, in which a gnetic male has secondary female sex
characteristics.
Ovaries: They are also controlled by FSH and LH, and produce estrogens and progesterone.
Estrogens are repsonsible for development and maintenence of secondary sexual
characteristics, thickening of endometrium for preparation of implantation, development of
female reproductive tract, and are secreted by ovarian follicles and the corpus luteum.
Progesterone- secreted in response to LH stimulation, released from the corpus luteum (remant
follicle on the ovary surface), responsible for development and maintenace of endoemtrium, bu
tnot generation. By the end of the first trimester progesterone is supplied by the placenta and
corpus luteum stops functioning.
Each mont the endometrial lining grows shed in a cyclical manner, menstural cycle, controlled
by levels of E and P, and can be divided into four stages, the follicular, ovulation, luteal and
menstration.
The follicular phase begins when menstural flow stops. GnRH secretions in response to low
levels of E and P, which leads to FSH and LH, develop ovarian follicles, which produce mostly
E, which causes negatigve feedback of GnRH, and E works to regrow endometrial lining,
stimulating vasculation and glandularization of the decidua.
During Ovulation estrogen has negative and positive feedback effects, late in teh follicular phase
follicles secrete more and more estrogen, eventually reaching a positive feedback elvel where
GnRH levels spike, which induces ovulation, the release of an ovum from teh ovary into the
abdominal cavity.
In the luteal phase, LH causes the ruptured follicle to form the corpus luteum which secretes
progesterone, so e helps regenerate endometrium but P maintains for implantation, P levels
rise, E levels stay high, which cause negative feedbck on GnRH, to rpvent development of
multiple ova,
If no implantation, human chorionic gonadotropin (hCG an LH analogue, will not be made, so
corpus luteum is no longer stimulated, and progesterone levels decline, uterine lining is shed,
and the low levels of E and P end the negative feedback of Gnrh.
hCG is used in preg tests.
If fertilization corpus luteum is maintained, by presence of hCG which is secreted by the
glastocyst and developing placenta. 1st tri E and P secreted by CL that keep uterine lining in
place, by 2nd tri hCG levels decline but E and P rise isnce they are now secreted by the
placenta itself. and high levels of E and P prevent further GnRH secretion.
Menopause resutls from decreased responsiveness of the ovaries to FSH and LH. Fewer
follicles will begin tod evelop each month and some may fail to rupture, leading to decreased
levels of E and P, and lose negative feedback so high levels of FSH and LH.
During ovulation E peaks, then FSH and LH peak, FSH to a lesser degree, and then P peaks
and E peaks again, then by menstration rates lower abruptly.
Pineal Gland-secreates melatonin, probably involved in circadian rhythems.
In the gastrointestinal tract, there is glandular tissue in teh stomach and intestine, and release
secretin, gastrin, and cholecystokinin, which are released after foot intake.
The kidney produced erhthropoietin, which stimulates bone marrow to increse production of
erythrocytes, in response to low O2 levels in blood.
Th heart releases atrial natriuretic peptide ANP, to regulate salt and water balance and the
thymus releases thymosin, important for T cell development and differnetiation.
Hormones can be petide, steroid or amino acid derived. Peptide are made of AA, and are
dervied from larger precursors that are celaved, transported to the golgi, site of modification,
direct it to the correct location in the cell, and released by exocytosis becuase they are charged
adn cannot just cross membrane. so also bind receptors on exterior of cell targets. and
stimulate production of secon dmessengers, like cAMP which can then bind to intracellular
targets like proteins or DNA to exert the hormones effect. The connection between hormone at
surface and the effect brought about by cAMP is known as signaling cascade, and there is a
possibility for multiplication. One hormone can bind to multiple receptor moelcules before
degraded. Each receptor can cativate several adenylate cyclases to make cAMP, making more
signaling. cAMP is terminated by phospodiesterase. CAMP has a short life but acts quickly.
Steroids are derived from cholesterol, and end in one or en, while peptides generally end in, in I
think. They are nonpolar so cross the membrane, receptors are intracellular or intranuclear, and
dimerize, with another receptor after bonding to the first, which can alter DNA transcription
increasing or decreasing depending on hormone and gene in question. the effects are logn lived
as they alter the amount o fmRNA and protein present in a cell, but longer lived as process of
transcription and translation are not as immediate.
Amino acid derivatives are hormones that come from one or two amino acids, with some
modification, and depending on poalrity can act like steroid or peptides.
Review:
PEG directly stimulate, Flat tropic
the parathyroid gland increases blood Ca2+ levels,
E is highest jsut before and after ovulation
Hypothyroidism in newborns is called cretinism
LH stimualtes ovulation, FSH does stimualt ethe maturation of ovarian follicles but LH stimualtes
the development of the corpus luteum from an ovarian follicle.
Too much aclcitonin leads to low levels of Ca in blood, muscle weakeness and slowness of
movement as well as CA deposits on bones best treated by raising PTH levels
Thyjus gland secretes hormone ssuch as thymosin which stimulate T cells which defend against
viral and fungal infections.
Chapter 13 The nervous System
Som ais the cell body of the nuern, housing nucleus, endoplasmic reticulum and ribosomes. The
dendrites are connected, the axon hillock is where the axon connects, a nerve fiber specialized
to carry electrical messages. Most mammalian neurons are insulated by myelin to prevent signal
loss, and increasing speed of conduction, it is produced by oligodendrocyts in the CNS and
Schwann cells in the periphery. The nodes of ranvier are the poitns between the mylenin sheath.
At the end is the nerve terminal or synaptic bouton. The space between neurons is the synaptic
cleft, or the synapse.
All or nothing action potentials. Neurons use selective permeability to ions and the sodium
potassiump ATPase to maintain a negative resitng membrane potential. Inside the neuron there
is much K but little Na. Outside Na is high but little K. The negative resting potential is generated
by negatively charged proteins and gerater permeability to K compared with Na. Since K
concentration is higher on inside it diffuses down its gradient out of the cell. So the K moves out
making the inside more negative but it sitll has more K but Na cannot enter to compensate. After
action potential we need sodium potassium ATPase to restore the gradient. They transport three
Na out fo the cell for two K into the cell at the expense of one atp because both move against
gradient.
To reveiw more Na outside more K inside atpase makes negative b/c 3:2 but ATp needed
because against concentration gradients.
As the information is integrated at the aon, depolarization or hyperpolarization can occur. Inhib
cause hyperpolarization. If it reaches threshold value (-55--45) an action potential is triggered,
and ion channels in the emembrane open voltage gated ion channels, Na and K are the ions.
First Na channels respond to depolarization, higher concentration outside, and thse inside is
negative so electric and chemical gradient. The cell becomes positive, and at +35 mV the
Potassium channels are openned electrochemical gradient pushes it out. and then
repolarization, restoration of negative membrane potential. Often over shoot and hyperpolarize.
Neurons like muscles have refractory periods which are absolute. There is also a relative
refractory period where stimulation must be greater than normal to cause action potential.
Impulse propagation occurs because as the soidum from the axon hillock rushes in, it causes
depolarization in the region surrounding it, which resutls in the opening of sodium channels
along the axon in a wavelike fashion and shut as potassium channels open at +35. The potential
doesnt move backwards becuase of refractory. The longer the axon and cross sectional area
the less resistance. The node of ranvier is where ions move. This is known as saltatory
conduction, moving from node to node.
Presynaptic terminal (neuron) and postynaptic. If its signals to a muscle or gland it is an effector
cell. The synapses are chemical in nature, using NTs, which are calcium dependent. To stop
effects of NT they can be broken dwon or use reuptake carriers to be recycled, and others
simply diffuse away.
Afferent neurons are sensory, while efferent are motor. Interneurons are involved in local
circuits. Many axons together make nerves, cell bodies also cluster. In the PNS collectionsa re
known as ganglia in teh CNS they are nuclei.
The central nervous system is composed of brain and spinal cord. The gray matter, is
unmylenated and white matter is ylenated. Divide brain into forbrain, mid and hind brain.
Forebrain, is the newest evolutinarily and is broken down into the diencephalon and
telencephalon. Telencephelon consists of the cerebral cortex, and inside is the diencephalon
which consists of thalamus and hypothalamus. Sensory info goes through the thalamus.
The midbrain passes sensory and visual info to the forebrain while receiving motor instructions
fromt eh forebrain and passing them to the hindbrain.
The hindbrain involuntary functions conissts of cerebellum, pons and medulla together called
the brainstem. It check that motor and snesory info align. The medulla modulates ventilation,
heart and gastrointestinal tone.
The spinal cordis divided into the cervical, thoracic, lumbar and sacral. It is protected by the
vertebral column. The spinal cord runs through the hollow column inside bones with nerves
entering and exiteing at each vertebra. So its also capable of reflex arcs because at dorssal end
receive sensory info and there is some gray matter which can transmit to ventral and motor
repsonse. The cell bodies of the sensory neurons are found in the dorsal root ganglia.
The PNS has 12 cranial nerbes, 31 spinal nerves and divide peripheral innervation between
somatic and autonomic, Somatic is voluntary movement, The interface between effector cell and
muscle is neuromuscular junction. The SNS also does refleces which can be monosynaptic or
polysnaptic. Mono is when a single synapse between sensory neuron, and motor neuron that
responds, Polynaptic is when there is at least one interneuro So for withdrawl reflec
monosynaptic to jump off thumb tack but opopsite leg must be stimulated to stabilize. The
interneuron is in the spinal cord.
The ANS controls smooth and cardiac muscle. ANS is a two neuron system, a motor neuron in
teh SNS goes directly ot th emuscle without snyapsing, in teh NAS two nuerosn work to transmit
the first is the preganglionic and the second is the post ganglionic neurons. the Pre has its soma
in teh CNS while the axon travels to a ganglion in the PNS. The ANS can regulate each organ
individually or it can coordinate its effects.
The sympathetic nervous system is responsible for fight r flight, increase blood flow to herat and
skeletal muscle, breath rate and heart rate, pupils dilate so keep eyes on bear, pregang use
acetylcholine while post gang use norepinephrine.
The parasympathateic nervous sytem does the opposite, the vagus nerve, one of the 12 cranial
nerves is responsible for the effects in the thoracic and abdominal cavities. pre and post
ganglionic neurons use acetylcholine as NT.
Sensory neurons come in three varieties, interoceptors, proprioceptors and exteroceptors,
monitoring internal environmen tparametrs like blood volume, pH and Co2, position of body, and
light soudn touch test and pain and temp resepcitvely. nociceptors also sense pain and relay
that information to the brain.
The eye detects light, covered by sclera, which is the white, but doesnt cover the cornea, The
choroid is beneath the sclera and provides nutrients and O2, and beneath that is the retina
which contains the photoreceptors. Light first passes the cornea, that bends and focuses it, then
through pupil, the msucular pigment is the iris which adjusts amount of light entering the eye,
then through the lenswhich focuses the image on the retina. Cones and rods are
photoreceptors, rods have only rhodopsin which explain monochromatic nature. After excitation
by light they send a signal to bipolar cells, which relay info to the retinal ganglion cells, which
bundle to form the optic nerve, which is the location fo the blind spot. The aquesous humor and
vitreuos humor make light transmission easier.
The ear Tranduces sound waves, into electrical signals, the outer ear channels sound to the
tympanic membrane which starts the middle ear and includes the ossicle, malleus, incus, and
stapes, which transmit info through vibrations to the oval window to the fluid filled inner ear
made of the cochlea and semicircular canals, which create fluid waves that depolarize hair cells,
and sned siglas down the auditory nerve to the brain.
The semicircular canals are improtant for balance, there are three for each dimension and are
fileld with endolymph, putting presure on hair cells in different ways maintaining balance and
processing acceleration.
Olfaction and gustation, taste buds are composed of 40 epithelial cells, on the tongue, soft
palate and epiglottis. The outer surface of taste buds contain a taste pore, from which microvilli,
taste hairs protrude. we taste sour, salty sweet and bitter. Respond to all four but preferentially
to one.
Smell olfactory hairs or cilia project, chemicals bidn to receptors, project to olfactory bulb in
brain.
Review:
Organ of Cort is the structure that trasnduces pressure to action potentials.
To increase intensity of stiumulus increase frequency of action potential.
The cell is has a greater permeability to K+ then Na+ so there are more K+ inside the cell and
other ions help maintain the negative resting potential.
Chapter 14
True breeding-offspring always have same traits
Mendels Four Tenents: genes exist in alternative forms (alleles), An Organism has two alleles
for each gene one from each parent, The aleles segregate dureing meiosis resulting in
gameetes that only carry one allele, and if two alleles in an individual organism are different only
one will be fully expressed (dominant versus resessive)
A cross of only one trait is said to be monohybrid, there is a parent generation followed by a
fillial generation. Then a Fillial 2 generation. If the F1 generation crosses with itself its called an
self-cross.
Test-cross (back crosses) for unknown genotype by crossing it with a known resessive.
We can also do a dihybrid cross, using Mendels law of independent assortment, meaning the
genes are not correlated.
On allele is located on one chormosome and the other is located on the homologou
schromosome of diploid speceies.
The replicated DNA is held together at the centromere, together known as sister chromatids.
and homologous pairs of chromosomes line up in metaphase I and then seperate during
anaphase I. Homologou spairs seperate, reductional division, but chormatids attached until
meisosis II but independent assortment occurs during meiosis I.
Frequency of recombination can range from 0% completely linked, to 50% completely unlinked,
caused by crossing over, exchange of DNA between homologous chormosomes paired during
meiosis. The distance between gene loci determine the degree of genetic linkage. So tightly
linked genes recombine at freq close to 0. One map unit corresponds to a 1% chance of
recombination.
Incomplete dominance is when heterozyg end up a mixture, red and white in plants end up pink.
For co-dominance there must be multiple coding alleles for a gene and more than one alleles
must be dominant when expressed with a recessive allele. When two dom together both
expressed like ABO blood. So there are three coding alleles but only two alleles in any partiuclar
individual.
Penetrance and Expresivity deal with interplay between genes and environment. Penetrance is
the number of individuals carrying the allele who express the phenotype. Huntingtons is
dominant but 5% dont express symptoms but it is highly penetrant.
Expressivity is when have the genotype but exresss to a varying degreee. So you could have all
the syptoms, highly expressed or few.
Recessive diseases stay in gene pool better, especially since in case of sickle cell more
resistant to malaria.
Dominant diseases must be late acting to remain in population, like huntigtons.
22 aytisines abd 1 sex chromosome, sex determined by pops because maybe contribute Y. A
sex linked trait is hemizygous for men, because despite only on one allele still expressed. There
are frew X linked dominant diseases, if a mutation on the Y then all males will ahve the disease.
For sex-linked use X'Y '= carrier.
On a pedigree males are squares, and shaded means affected. Carriers are half shaded. IF only
males probably sex linked.
In humans diploid number is 46 chromosomes. variations are aneuploid, most commonly
caused by nondisjunction. If during meiosis I homologou schormosmes or doruing MII sister
chormatids fail to seperate, extra gneetic material. If the problem was in M2 we could get
trisomy or monosomy if its the 21st tri is down syndrome.
For sex chromsomes, females may be born with a single X, short and sterile, or an extra X,
metafemales or superfemales, can be retarted and sterile. Kilnefleter males are XXY and ar etall
develop breasts and undescended testes. XYY is also possible and are taller.
Chomosomes can be damaged by environmental factors like X-rays and chemo, losing material
is called deletion. The lost fragment may join to ta homologous chomosome known as
duplication, or a totally different chormosome known as atranslocation. It can also find its way
back but in reverse, inversion. If in the germ line this is passed on.
Review:
For a test cross we can also use heeterozygous.
Recombinants are genotypes not found in the parent generation
Chapter 15 Molecular Genetics:
DNA is a polymer with the asic unit of a nucleotide that consits of deoxyribose sugar, a
nitrogenous base and a phsopahate group. The sugar is in the middle, the nitrogenous bases
are ACGT, Cytosine and thymine are single ringed pyrimidines, adenine and guanine are double
ring purines. (cut the pie) CUT are py
If the nitrogne base is the primary carbon, the three prime connects to the phosphate of a
different nucleotide and the five prime connects to the phosphate above.
Deoxyribose sugar because the 2' has an H instead of OH but according to th ebook the 3' and
5' are OH. They loose H and make connections. The two stands of DNA is antiparallel, So one
strand appears 5'-3' and the other 3'-5'.
DNA undergoes semi-conservative replication. Each new helix containing a strand from the
parent DNA and a newly synthesized strand. Because there are so many bases, DNA first
unwinds in multiple origins of replication, to allow for efficient replication. The gneeration of DNA
proceeds in both directions creating replication forks, because looks like fork in the road.
Helicase is the enzyme that unwinds the helix, to keep from reforming, single strqand binding
proteins stabilize the singles. But unwinding can cause positive supercoiling that strains the
DNA helix, DNA gyrase relieves this by introducing negative supercoils. Then RNA primer which
is several nucleotides logn comes along, which is made by primase, an RNA polymerase, is th
enzyme that generates the RNA primer, so tha tthe DNA polymerase can start adding individual
nucleotides. The first nucleotide bind sto the 3 prime end of the primer chain.
DNA polymerases are a number of different enzymes that catalyze the process and it also cuts
the phosphodiester linkage of a new nucleotide triphosphate to incorporate the new base.
The 3'=5' whose complement is 5'-3' is fine for DNA polymerase and forms the leading strand.
But the 5'-3' strand would have to make 3'-5' and DNA polymerase cannot, so small sections
known as okazaki fragments, (1000 base pairs) are produced at at ime. The primer is
introduced as far forwards as possilbe and dna polymerase works back towards the origin of
replication and forms th elagging strand. So the lagging strand is produced discontinuously
through the formation of okazaki framgents. The summation of okazaki framents is in the 3'-5'
direction and the samll gaps between the fragmetns are filled with nuecleotides and the sugar
phosphate backbone is added by DNA ligase.
RNA has three amjor difference, generally single stranded, U instead of T, and ribose instead of
deoxyribose, it can be found in both the nucleus and cytoplasm and participates in transcription
and translation.
mRNA (messenger) carries genetic message from nuc to cytoplasm to be translated into a
protein. In eukaryotes, mRNA is monocistronic, each has one product, while in prok a few
proteins can be fromed by starting translation at different spots on mRNA>
Transfer RNA (tRNA) is found in the cytoplasm and ther eis a differnet tRNA for each amino
acid.
Ribosomal RNA rRNA is synthesized in the nucleus, and is important for ribsoomes used for
protein assembly.
hnRNA (heterogeneous Nuclear rna is the precurson to mRNA.
Transcription-DNA cannot leave the nucleus, so encoding of mRNA is known as transcription.
First the DNA helix is unwound, and the antisense strand is used, and can only occur 5'-3' and
is catalysed by RNA polymerase. Specailized DNA regions, promotoers, signal where to being
transcription as well as termination sequences, to indicate where to stop. The product is hnRNA.
Before it can leave the nucleus a 5' guanosyl cap is added to stabilize the starting end, a poly
adenine tail is put on the 3' end and finally the introns are removed, exons are coding part sof
the genome while introns are nonsense.
Each three letter combo of ACC for example represents a protien. There are 20 amino acids but
64 options which leads to degeneracy aka redundancy. The triplet word is known as a codon.
Translation: the process of builiding the protein sequence requring, mRNA, tRNA, ribosomes,
amino acids and energy.
tRNA- shuttles the correct AAto the ribosome when needed, so it can recognize both the codon
adn the amino acid that it translates into. So on on eend there are nucletides that are
complementary to th ecodon, they are known as anticodon, and on th eopposite side tRNA is
bound to the AA that corresopnds.
Codons and anticodons are always written 5'-3'
Each tRNA has a CCA nucleotide sequence where the AA binds, this is accomplished by using
the tRNA synthetase enzyme that binds the AA to the tRNA using GTP, the result is aminoacyl
tRNA complex.
Ribosomes are composed of two subunits, both made up of ribosmal proteins and rRNA. The
large and small subunits bind together during protein sythensis. They ahve three binding sites,
one for the mRNA and the other two for the tRNA. The binding site for the tRNA are the A site
which holds the aminoacyl-tRNA complex, and the P site which binds to the tRNA which binds
to the attached to the growing polypeptide chain. So three stages, intiiation, ellongation and
termination.
Initiation-mRNA seeks out a small ribosome, and bind in the presence of initiation factors and
the samll ribosome slides along the mRNA until it reaches the start codon AUG. The initiation
aminoacyl-tRNA complex, methionine tRNA pairs with the start codon. Then the large ribosomal
subunit joins the complex, completing the ribosome. The tRNA is in the P site.
Elongation- Once the complex is formed the ribosome slides along the mRNA adding new
amino acids as it goes. Hydrogen bonds form between the mRNA codon in the A site and the
tRNA anticodon filling the A site, and ther eis a charge aminoacyl tRNA in both the A and P
sites. The enzyme peptidyl transferase, uses the energy stored in the amino-acyl tRNA complex
when the amino acid was loaded, having used GTP, to catalyse the formation fo the peptide
bond. the aminoacyl-trna used for this is the one in the P site and the bond is made between the
single AA in the A site and the methionine int he P site. Translocation is necessary to add the
next amino acid residue. The ribosomal assembly slides in a 5'-3' direction along the mRNA,
moving th next codon into place in the A side, the uncharged tRNA in the P site is expelled adn
the aminoacyl tRNA is moved to the P site.
Termination- translation has stop signs, using termination codons, if the codon in the A site is
UGA, UAA or UAG. and instead of tRNA a protein called release factor binds to the termination
codon casuing a water molecule to be added to the polypeptide chain. The polypetide chain is
released fromt eh tRNA in the P site and the ibosomal subunits dissociate. Sometimes multiple
ribosomes may translat ea message at the saem time, polyribosome.
The polypetide then folds into a secondary structure based on lowest energy conformation, and
can be cleaved or have sugars added to it. Other modifications like phosphorylation,
carboxylation and methylation are all possible.
Possible mutations include, base pair mutations, insertions and deltions. mutations are also
called point mutations, whereas insertions and deletions are known as frameshift mutations.
Point mutations involve a single nucleotide and if no effect are called silent mutations, b/c of
degenerecy. A missense mutation is when one amino acid is substituded for another. So point
mutations can either be missense or silent.
Frameshift-codons consist of 3 nucleotides, aka a reading frame, usually more serious,
Mutagenesis, new mutations can arise from DNA polymerase making a mistake, UV rays, or
transposons can remove and insert themselves into the genome possible in the middle of a
coding sequence. Insertions and deletions can be of one base pair or more.
Viruses come in sing or double stranded DNA or RNA and can vary in number of jeans but they
are specific as with regards to host cells. For example only neurons.
Viruses dont reproduce on their own, but invade a host cell and hijack its machinery. Viruses
can only infect cells that have receptors that recognize the viruses protein coat, capsid. Different
viruses inject different amount of material into cells. Viruses like HIV completely insert, while
bacteriophages only insert gnetic material, leaving the capsid outside. DNA viruses hav elife
easier as they enter nucleus and make use of DNA and RNA polymerases found there. Some
DNA viruses carry out replication in cytoplasm and brign their own polymerase.
RNA containing viruses sometimes bring RNA replicase with them, while otehrs wait for the
enzyme to be translated from their own gneome, which acts as mRNA. A subclass, retrovirsues,
create a DNA copy using an enzyme called reverse transcriptase creating dna from rna, literally
reverse of normal transcriptase. The DNA is then integrated into the hosts DNA> So to remove
the virus the host must destory the whole cell. Using all the RNA and AA of the host cell the
transcribed genes are now translated into proteins, which allow for creation of new viral particles
called virions.
The viral progeny can be released because the host cell may lyse as a result of being filled with
viral particles or the viral invasion can initiate apoptosis. A virus can leave the cell by extrusion,
which is like budding off of the plasma membrane. This allows the cell to live and is known as
the productive cycle.
Bacteriophage specifically target bacteria, inserting DNA while keeping viral enevelopes and
other sturctures outside of the cell by boring a hol ein teh bacterial surface. Depending on the
growth cycle of the virus it can be lytic or lysogenic. They are similar to lysis and productive
cycle. Bactereophase lyse the cells during the lytic phase. During the lytic cycle the virus makes
maximal use of cells machinery with little regard for damage to the cell. Once the hos tis swollen
with virions the cell lyses, and bacteria in the lytic phase are called virulent.
If the virus does not lyse the bacteria, it can integrate into the hos tgenome as a provirus, so as
bacteria reproduces the virus will too. It can remain indefinitly, but at some point environmental
factors cause the provirus to leave the genome and revert toa lytic cycle. Some viruses are not
so harmful, and once have one in genom eless likely to get a second more lethal superinfection.
Bacterial genetics- they are prokaryotes, single celled organisms containing circular DNA
genome, localized in the nucleoid region, and no membrane bound organelles. They also have
extrachromosomal material known as plasmids, episomes are a special type that can integrate
into the genome. There is no gap between transcirption and translation and there are
polycistronic messages, multipl eproteins for same mRNA. For replication bacteria are much
smaller so only one origin of replication, and can occur in both directions quickly.
Under favorable conditions bacteria utilize binary fissin, which is asexual to increase their
numbers rapidly, but genetically identical. To increase diversity there is transformation (where
foreign plasmid is integrated into the host genome), conjugation (where there is mating like
sexual reproduction involving a cytoplasmic bridge, where male donor donates to the recipient
female, made from appendagies called sex pili found on the male, which to form the bacteria
must contain sex factors plasmids, in E coli the sex facto ris called the F factor and cells that
have it conjugate with F- cells and replicate the F factor and then pass it along making the Fcell F+ [sometimes the sex factor is transormed into the hos tgneome, when conjugation occurs
the entire genome replicates and attmepts to transfer into the recepient, usually
unsuccesfullybut these cells are referred to as Hfr fo rhigh frequency of recombination]), and
finally transduction where bacteriophages excise from gneome and take along some bacterial
genome sometimes whole genes, and when infect new bacterium, new hos twill receive new
genes.
Prokaryots regulate at the transcriptional level to regulate metabolism. The ability to transcribe a
gene is based on the RNA polymerase's access to the genome. Operons direct this process and
ar emade up of structural genes, an operator gene and a promoter gene. The structural genes
code for the protien of itnerest, for example lactase. NExt the operator site consiststs of a
nontranscribable region of DNA capable of binding a repressor, and the promoter gene provides
a place for the rna polymerase to bind. The repressor can bind to an opearator sequence and
act as a road block because RNA polymerase cannot get from the promoter to the structral
genes. The system can either be inducible or repressible. Inducible sstems require the
presenece of a compound known as an inducer to cause transcription, while repressers only
stop transcription when present,
In inducible systems, the repressor is always made but to remove the block an inducer must
bind the repressor protein so that RNA polymerase can move down the gene. They are similar
to compettive feeddback for enzyme activity so as we raise level of inducer, most of the
repressor will be bound to it rather than the operator sequence. So the gene only produces,
when it is needed. The laxtase operon codes for enzymes that allow a bacterium to digest
lactose in place of glucose, which is more energetically expensive bacteria us this only when
lactose is high and glucose is low, so enzyme only goe son when there is lots of lactose.
Repressible systems work based on negative feedback. The final structural product can serve
as a co-repressor, so not too much is made.
Review:
Remember that nucleotide includes the sugar and phosphate so on nucleotide in a single strand
of DNA is linked by phosphodiester bonds.
peptidyl transferase catalysed the formation of a petpide bond in protein synthesis.
All stages of translation require energy.
Topoisomers such as DNA gyrase are involved in DNA replication. DNA gyrase is a type of
topoisomerase that enhances the action of helicase enzymes by introducing negative
supercoils.
trp is an examply of a represser operon and is binded by tryptophan. lac operon is an inducible
operon.
Chapter 16: Evolution
Lamarck proposed use and disuse with respect to organs, leading to acquired characteristics,
but they are inherited not acquired.
Darwin: organisms produce offspring few of which survive to reproductive maturity, chance
variation is inheritable and can be favorable for survival, this leads to natural selection and
fitness based on reproductive success.
Darwin was not totally right as we do not have a small appendix because it is advantageous but
he was basically right and the accespted theory is known as neo-darwinism or modern
synthesis. This is Darwin witht heupdated understanding of mutation. The term is differential
reproduction where after time succesful organisms will become pervasive in the gene pool.
Punctuated equilib suggests that changes in species occur in rapid bursts rather than evenly
over time.
By relating the ages of differen tfossils and their anatomies and abudnances paleontolgoists can
determine chronological succession of species in the fossil record.
Biogeography-evolution not equal across the globe. Animals can migrate to a land and then
evolved speerately called divergence.
Analogous structures serve same function but evolved seperately, insects and birds flying.
Compartivie embryology-gills present in chordates which include fish birds and humans, we also
have tails in first four weeks.
Molecular bio shows that as species become more taxonomically distant the amount of shared
genome decreases.
How often an allele appears in a population is known as gene frequency. Evolution results from
cahnges in these gene frequencies in reproducing populations over time.
The population is large, there are no mutations that affect the gene pool, mating between
individuals in the population is random, there is no migration of individuals in or out of
population, the genes are equally succesful at reproducing, then the population is in hardy
weinberg equilibrium and we use a pair of equations to predict the allelic and pheontypic
frequencies.
If we assume two alleles, T and t and call p the freq of T and q the freq of t then p+q=1 and we
can square both sides where p squared is the frequency of TT 2pq is the frequency of Tt and q
squared is the freq of tt P^2+2pq+Q^2=1
There should always be double the amount of alleles as population for each person has 2
alleles. These equations show that if no microevolution is occuring the gene frequencies will
remain constant from generation to generation. So the first equation give syou frequency of
alleles but the second gives you the actual genotypes of the population. We can show using a
punnet square that this is true using p and q as the alleles of the parents.
There are five agents of microevolution that make Hardy Wein purely hypothetical. Natural
selection, some will be able to reproduce more than others in gene pool. Mutations-change
allele frequencies in a population shifting equlibria. Assortive mating, mates are chosen based
on proximity and phenotype.
1/300 people are carreirs of taysachs so multiply 1/300 and 1/300 and 1/4 for the fact that its
recessive. but ashkenaz raise rate.
Genetic drift-cahnges in composition due to chance, more pornounced in small populations
Gene flow-migration of individuals between poplations result in al oos or gain of genes and
change composition of gene pool.
Natural selection is the only method capable of gneerating stable evolutionary chagnes over
logn period ds of tiem rather than short. It can occur as stabilizing, direction or disruptive
selection.
Stabilizing selections work to keep phenotypes within a specific range by eliminating extermes,
for example human birth weight is maintainged within a narrow band by stabilizing sleection.
Fetuses that weigh too little or too much will not live.
Directional selection-as a result of differential survivorship some mosquitos will be resistant to
DDT and now most are.
Disruptive selection-is when both extremes are selected over the norm, large or small beaks on
Galapagos.
Altruism-larges castes that are sterile for the sake of the community like in ants and bees, but its
impossible that a sterile gene gets passed on, so group selection with gene for sterility was
rejected. Kin selection suggestst hat organisms will behave altruisitically if they are closely
related to succesful reproducing organisms, because related to fertile queen. Inclusive fitness
refers to the number of alleles an individual passes on to the next generation even if only
indirectly through altruistic bheavior.
Speciation is the emergence of a new species that can mate with each other but nto with
members of other species. This arises if geographically secluded and repodcutive isolation.
prezygotic mechanisms prevent formation of zygote completely while postzygotic mechanisms
allow for gamete fusion but yield inviable or sterile offspring.
Prezygotic isolating mechanisms include temporal isolation, like if the two mate at different
seasons or times of day.
Ecological isolation if they live in different habitats and rearely meet and cant mate.
Bheavioral isolation is if the two species are not sexually attracted to each other because of
differences in pheromones and courtship displays.
Reproductive isolation is if the gnetilia of two species are incompatible.
Gametic isolation is if intercourse can occur but fertilization cannot.
Postzygotic isolating mechanisms include hybrid inviability is if zygote is aborted. Hybrid
sterilitity is if the offspring is sterile.
Hybrid breakdown is if the first generation are viable but second are inviable.
Adaptive radiation is when one species gives rise to many different. Each species diverges and
oocupies a unique ecological niche. THis quick evolution decreases competition between
species.
Patterns of evolution include divergent, parallel and convergent. Convergent refers to
indpendent development of similar characteristics without sharing a common anscestor. Fish
and dolphins resemble each other physically but different classes of vertebrate.
Divergent evolution is if indepndent development of dissimilar characteristicsfor example seals
and cats are both mammals.
Parallel evolution is when related species evolve in similar ways for a logn time in response to
analogous environmental pressures.
The earliest evidence of life is in stromatolites, with evidence of photsynthetic bacteria 3.5 billion
years ago.
Dudes believed that conditiosn of early Earth favored the creation of organic molecules such as
simple AA. The mixture of O, N H and C is called primordial soup, because these atoms were
found in high concentrations in the seas. Furthermore there was much energy from sun,
lightning, radioactive decay and volcanic activity, thus bonds formed. Experiments proved this to
create AA.
Furthermore, polymers in an aqueous solution were found to assemble into tiny proteinaceous
dropets called microspheres, which had selectively permeable membranes. Colloidal droplets
called coacervates were formed from a solution of polypetptides, nucleic acids and
polysaccharides capable of enzymatic activity, but they were not living cells. The collection of
organic polymers bleieved to have been the primitive ancestors of cells are called protobionts.
They would have been able to grow and divide but did not hav ea way of transmitting info to the
next generation. It is believed that RNA comes in here as free bases can allign with
complementary based on a short sequence, then AA probably came to associate with RNA
sequences and onwards to humans...
Review:
Part of Darwins theory of natural selection is that organisms become seperated groups
depending on how adapted they are to a particular environment and these groups eventually
seperate to become distinct species. There should be no mention of individuals with Darwin.
Analogous structures versus convergent evolution.
To review abiotic is something non living in environment, and abiotic polymers in aqueous
soluton were found to assemple into microspheres which had selectively permeable
membranes.
A coacervate is a tiny spherical droplet of assorted organic molecules (specifically, lipid
molecules) which is held together by hydrophobicforces from a surrounding liquid. They are not
the same as microspheres.
Review for Chem: What is the difference between a transition state and an intermediate.