ANATOMY AND
PHYSIOLOGY
Lecture
CHAPTER 1
The Human Organism
o
o
o
Abdomen
Arm
All systems simultaneously
Two-general ways of Anatomists
examine internal structure of living
person.
1. Surface Anatomy
• External features
• Body projections
• Sternum (breastbone)
2. Anatomical Imaging
• Use of;
• X-rays
• Ultrasound
• Magnetic resonance imaging
(MRI)
Both surface and imaging anatomy
provide important information for
diagnosing disease.
Physiology- Study of nature
•
Dynamic
Deals with the process or functions of
living things.
Two Major goals when studying
physiology
1.1 Anatomy and Physiology
Anatomy- Structure of the body
•
Parts and chambers of the body.
Anatomy means to dissect, cut apart and
separate.
Two Approaches of Anatomy
1. Systemic Anatomy
• Body by systems
o Cardiovascular
o Nervous
o Skeletal
o Muscular
2. Regional Anatomy
• Body organization
o Head
1. Examining the body’s responses to
stimuli.
2. Examining the body’s
maintenance of stable internal
conditions.
1. Human Physiology- Study of humans
• Anatomy
• Physiology
1.1 Cellular Physiology
• Focuses on processes
inside cells
• Manufacturing of
substance (Proteins)
1.2 Systematic Physiology
• Focuses on the
functions of organ
systems
1. The simplest level of organization
in the human body is the atom.
2. Atoms combine to form
molecules.
3. Molecules aggregate into cells.
Cells form tissues.
4. Which combine with other tissues
to form organs.
5. Organ work in groups called organ
system.
6. All organ systems work together to
form an organism.
1.2 Structural and Functional
Organization of the Human Body
Body’s six structural levels
1. Chemical Level
• Structural and functional
characteristics
• Determined by chemical makeup
• Involves; atoms; hydrogen and
carbon; molecules
Molecules structures determine its
function.
2. Cells Level
Cells- basic structural and functional
units.
Organelles- cells contains smaller
structures inside them.
•
•
Carry out particular function.
Digestion and movement of the
cell.
Microbial Cells- life form that can
only be seen in microscope.
•
•
One microbial cells for every cells
in body.
40 trillion in every 2 to 6 pounds,
body weight.
2.1 Three domains of living
organisms.
2.1.a Bacteria
• Genetic material not
separated from the rest of
the cells by a barrier.
2.1.b Archaea
•
•
Constructed similarly to
bacteria
Shares certain structure
called ribosomes with
eukaryotic cells.
2.1.c Eukarya
•
Structural complexity with many
smaller structures called
organelles.
“Prokaryotic is used to describe bacterial
and archaea cells”
3. Tissue Level
• Group of similar cells and
materials surrounds them.
3.1 Four classified makeup tissue
3.1.a Epithelial
3.1.b Connective
3.1.c Muscle
3.1.d Nervous
4. Organ Level
• Composed of two or more tissue
(The heart, stomach, liver and urinary
bladder)
5. Organ System Level
• Group of organs
(Example: Urinary system consists of;
kidneys, ureters, urinary bladder and
urethra)
Major Organ Systems;
1. Integumentary
2. Skeletal
3. Muscular
4. Nervous
5. Endocrine
6. Cardiovascular
7. Lymphatic
8. Respiratory
9. Digestive
10. Urinary
11. Reproductive
4. Growth
• Increase in the size or number of
cells.
Example: Bones grow when the number
of bone cells increases and the bone cell
become surrounded by mineralized
materials.
5. Development
• Changes an organism
• Beginning: Fertilization
• End: Death
The body’s major organs include the
brain, lungs, heart, liver, pancreas,
spleen, stomach, gallbladder, kidneys,
large intestine, small intestine, urinary
bladder and urethra.
1. 3 Characteristics of Life
-Most important feature of all
organisms is life.
Six essentials characteristics of life:
1. Organization
• Specific interrelationships
• Composed of one or more cells.
Disruption of this organized state can
result in loss of functions.
2. Metabolism
• Ability to use energy
Human cells possess specialized proteins
that can break down food molecules to
use as a source of energy.
3. Responsiveness
• Sense the changes
• External or internal
environment
• Adjust to those changes
Example: Body temperature rises, sweat
glands produce sweat, which can lower
body temperature down to the normal
range.
Differentiation involves changes in cells
structure and function from an
immature, mature and specialized state.
6. Reproduction
• New cells
• New organism
Reproduction of cells allows for growth
and development. Formation of new
organisms prevents extinction of species.
1.4 Homeostasis
Homeo- The same
Stasis- To stop
•
•
Actively regulate body conditions.
Maintenance of variable around
ideal normal value or set point.
1. Variables
• Changes in environmental
conditions
2. The homeostasis mechanisms
• Maintains body temperature
3. Set point
• Near ideal normal value
4. Normal Range
• Body temperature increases and
decreases
5. Negative Feedback
• Homeostasis is maintained
3. Effector- sweat glands, can adjust
the value of the variable when
directed by the control center.
Stimulus
•
•
Variable changed
Initiates homeostatic mechanism
Negative and Positive-Feedback
Mechanisms:
(Example of negative feedback)
Example: Body temperature is too high,
so sweating occurs. Negative feedback
Stops the sweating when the body
temperature returns to normal.
6. Negative-feedback mechanisms
• Maintain homeostasis
• In everyday terms: Negative
means “bad” or “undesirable”
• In this context: Negative means
“to decrease”
• “Negative feedback” is when any
deviation from the set point is
made smaller or is resisted.
Example: Normal body temperature
Three components of negative feedback
mechanism
1. Receptor- monitors the value of
variable (body temperature by
detecting stimuli).
2. Control center- part of the brain,
determines set point for variables
and receives input from the
receptor about the variable.
(Example of positive feedback)
Negative-Feedback Control of Body
Temperature
7. Positive Feedback
• Response to the original
stimulus.
• Results in the deviation from
the set point becoming even
greater.
• Positive means “increase”.
Thrombin- Responsible for blood clot
formation.
Two basic principles about homeostatic
mechanisms
1. Many disease states result from
the failure of negative-feedback
mechanisms to maintain
homeostasis.
2. Some positive-feedback
mechanisms can be detrimental
instead of helpful.
1.5 Terminology and the body plan
Foramen “latin word” “hole and
“magnum” means “large”
Foramen magnum – large hole in the
skull
1. Body Positions
Anatomical Position
•
Person standing upright with the
face directed forward, upper
limbs hanging to the sides and
palms of hands facing forward.
Supine - Lying face upward
Prone - Lying face downward
2. Directional terms
(Directional Terms)
3. Body parts and regions
Superior – above
Inferior - below
Anterior - in front of
Posterior – behind
Proximal – close to
Distal – far from
Anterior view
Posterior view
Quadrants
Medial – toward the midline
Lateral – away from the midline
Superficial – structure close to
the surface of the body
Deep – toward the interior of the
body
3.1 Body parts and Regions
•
•
Right-upper quadrant
Right-lower quadrant
•
•
Left-upper quadrant
Left-lower quadrant
Abdomen subdivided into regions (four
imaginary lines)
•
•
Two horizontal
Two vertical
Nine regions
Central region
•
•
•
Head
Neck
Trunk
o Thorax (chest cavity)
o Abdomen (contains organs)
o Pelvis
•
•
•
•
•
•
Right and left hypochondriac
Right and left lumbar
Right and left iliac
Epigastric region
Umbilical region
Hypogastric region
Upper Limb
•
•
•
•
Arm (elbow to shoulder)
Forearm (elbow to wrist)
Wrist
Hand
Lower Limb
•
•
•
•
Thigh (hip to knee)
Leg (knee to ankle)
Ankle
Foot
Abdomen quadrants and regions
3.2 Planes
NOTE: CONTRARY TO POPULAR USAGE,
THE TERMS ARM AND LEG REFERS TO
ONLY A PART OF THE LIMB.
Abdomen divided (four quadrants)
(Imaginary lines)
•
•
Horizontal
Vertical
•
•
Imaginary flat surface
Divides or sections the body to
make it possible to “look inside”
and observe the body’s structures.
•
Dorsal body cavity
Encloses the organs of the nervous
system (brain and spinal cord).
Two-subdivisions
1. Cranial cavity – houses the brain
2. Vertebral canal – houses the spinal
cord.
BOTH BRAIN AND SPINAL CORD ARE
COVERED MEMBRANES CALLED MENINGES
Ventral body cavity
•
•
Planes of section of the body
Sagital – separates the body into right
and left halves
Median – passes through midline of the
body
Transverse (horizontal) – parallel to the
ground
Frontal (coronal) divides into anterior
and posterior
3.3 Organs
• Revel the internal structure
Longitudinal – Cut length (cutting hot
dog bun)
Two-subdivisions
1. Thoracic cavity
2. Abdominopelvic cavity
Thoracic cavity
•
•
1. Pleural cavities – encloses lung
and surrounded by the ribs.
2. Mediastinum – houses the heart
and its major blood vessels
(thymus, trachea and esophagus).
Abdominopelvic cavity
•
•
Oblique – cut diagonally across the long
axis’s
•
•
•
Dorsal body cavity
Ventral body cavity
More superior to the
abdominopelvic cavity.
Houses primary the heart and
lungs.
Subdivided into sections
Transverse – cross section (cutting hot
dog into round pieces)
3.4 Body Cavities
• Contains internal cavities
Vast majority of our internal
organs
Collectively referred to as the
viscera
Houses within peritoneal cavity.
Contains majority of digestive
organs (stomach, intestines, liver
and spleen).
Encloses abdominal muscles consist
of;
1. Superior abdominal cavity
2. Inferior pelvic cavity
Serious Membrane of the Ventral Body
Cavity
Serous – In contact with membranes
•
Doubled layered membranes
Parietal – Layer of lines the walls of the
cavities.
Visceral serous membrane – Layer
covering the internal organs.
2. Pleural cavities
• Pleuron side of the body
• Houses a lung
Parietal serous membrane lining the
pleural cavities called the parietal
pleura.
Visceral serous membrane covering the
lungs called visceral pleura
The space between the two pleural
membranes is called the pleural cavity
and is filled with pleural fluid.
3. Peritoneal cavity
• Houses many internal organs (liver,
digestive organs, reproductive
organs).
Trunk Cavities
3.5 Serous Membranes
Parietal serous membrane in the
peritoneal cavity is called parietal
peritoneum.
Visceral serous membrane is called
visceral peritoneum.
The space between two serous
membranes is the specific location of
the peritoneal cavity and is filled with
peritoneal fluid.
Thoracic Cavity Membranes
•
Named specific cavity and organs
they are in contact with.
1. Pericardial cavity
• Containing heart is housed in
the mediastinum.
Parietal serous membrane is called
parietal pericardium.
Visceral serous membrane is called
visceral pericardium.
•
•
Space between two pericardial
membranes called pericardial
cavity.
And it’s filled with pericardial
fluids.
Mesenteries – provides a pathway for
nerves and blood vessels to reach
digestive organs.
THIS REGIONS OF DOUBLE-FOLDED
VISCERAL PERITONEUM IS CALLED
MESENTERIES.
Retroperitoneal – location and include
the kidneys, ureters, adrenal glands, a
large portion of pancreas, parts of large
intestine and urinary bladder.
Conditions caused by inflations
1. Pericarditis – inflammation of the
pericardium
2. Pleurisy – inflammation of the
pleura
3. Peritonitis – inflammation of the
peritoneum
CHAPTER 2
The Chemical Basis of Life
About 96% of the body’s weight
results from the elements oxygen,
carbon, hydrogen, and nitrogen.
•
Atom – smallest particle of an
element that has chemical
characteristics of element.
2.1 c: Atomic Structure
• Atoms – composed of subatomic
particles (some electric charges).
• Electrical charge – tendency of
particles to be attracted to each
other.
Two type of electrical charge
1. Positive
2. Negative
2.1 Basic Chemistry
•
Chemicals make up the body’s
structures and the interactions of
chemical with one another are
responsible for the body’s
function.
Chemical Terms
•
•
•
•
Nerve impulse generation
Digestion
Muscle contraction
Metabolism
2.1 a: Matter, Mass and Weight
• Matter – occupies space and has
mass.
• Mass – amount of matter in an
object.
• Kilogram (kg) –international
unit of mass
• Weight – gravitational force on the
objects given mass.
2.1 b: Elements and Atoms
• Element – simplest type of matter
having unit chemical properties.
Common elements in the human
body
Three major parts of subatomic particles
•
•
•
Neutrons – no electrical charges
Protons – one positive charge
Electrons – one negative charge
Since each atom has an equal number of
protons and electrons, the positive and
negative charges cancel each other.
Therefore, each atom is electrically
neutral.
•
Nucleus – where protons and
neutrons are found in the center of
atom
• Nucleus accounts for 99.97%
of an atom’s mass
•
Electron cloud – where electrons
are found.
There is a number of electrons that
each shell can hold.
Other shells do not contain electrons
until the inner shells have reach their
maximum.
•
•
Hydrogen, carbon and oxygen
atoms
•
Atomic number – number
protons in each atom.
of
The number of electron and protons in
an atom are equal, the atomic number
is also the number of electrons.
•
Mass number – adding the number
of protons and neutrons in each
atom.
Two ways of atoms achieve an octet
1. By transferring electrons between
atoms.
2. By sharing electrons between
atoms.
Example: carbon has 6 protons and 6
neutrons, its mass number is 12
(6+6=12).
Isotopes – Two or more forms of the
same element that have a same
number or protons and electrons.
Type of chemical bond
Relationship Between Electronegativity
and Chemical Bonding
•
2.1 a: Electrons and Chemical Bonding
- The simplest level of organization is the
chemical level.
•
•
Chemical bonds – Interaction
between atoms to form molecules
by either sharing or transferring
their outermost electrons.
Electron shells – Energy level are
often drawn as concentric rings.
Valence shell – outermost shell
o The number of electrons in
the
valence
shell
determines
an
atom’s
chemical behavior.
Octet rule – tendency of atom to
combine with other atoms until
reach has 8 electrons (2 electrons
for hydrogen).
•
•
Electronegativity – ability of the
atom’s nucleus to pull electrons
towards it.
Covalent bonds – are formed by the
sharing or electrons between
atoms
that
have
same
electronegativity
(nonpolar
covalent).
Ionic bonds – are formed by the
transfer of electrons between two
atoms that have very different
electro negativities.
Ionic bonding – number of protons and
electrons are no longer equal and a
charged particle.
Nonpolar covalent bonds
Ionic bonding
•
Ionic – bond forms when electrons
are transferred between atoms
creating opposite charged ions.
Nonpolar bond – distribution of electrons
due to the equal electro negativities of
the two atoms.
Molecules – formed by nonpolar covalent
bonds are neutral.
•
•
•
Nonpolar covalent – bond forms
when electrons are shared equally
between the nuclei.
Polar covalent bonds – where the
two atoms involved in a covalent
bond have different electro
negativities.
Polar molecules – polar covalent
bonds; electrically asymmetric.
Important ions in the human body
Molecules and Compounds
Covalent bonding
•
•
Covalent bond – forms when atoms
share one or more pairs of
electrons
Molecule – the result of sharing
electrons rather than transferring
electrons, atoms have similar
electro negativities
•
•
A molecule is formed when two or
more atoms chemically combine to
form a structure that behaves as an
independent unit.
Compound – Substance resulting
from the chemical combination of
two or more different types of
atoms.
Hydrogen bonds
Polar covalent bonds
•
A water molecule forms when one
oxygen atom forms polar covalent
bonds with two hydrogen atoms
Polar
covalent
bond
–
uneven
distribution of electrons due to the
stronger electronegativity of oxygen
compared to hydrogen
•
•
Molecules formed by polar
covalent bonds have charged
portions
The electron distribution is
unequal between the nuclei and
the electron density is greater
around the nucleus with the
stronger electronegativity
The positive hydrogen bond of one water
molecule forms a hydrogen bond with
the negative oxygen part of another
water molecule
As a result, hydrogen bonds hold
separate water molecule together
Intermolecular Forces
- Are the weak charge attractions
- Exist between separate molecules or
- Between ions and molecules
- Due to the attractions between
oppositely charged regions of molecules
(hydrogen bonds and the property of
dissociation)
•
Hydrogen bond – Essential for
several unique properties of water
Comparison of bonds
•
Dissociation
–
when
compounds dissolve water
ionic
Dissociate or separate – from each other
because the positively charged ions are
attracted to the negative ends.
•
Electrolytes – Dissociated ions
Dissociation
2.2 Chemical Reactions and Energy
-Reverse of a synthesis reaction and can
be presented in this way;
Chemical reaction – formation or
breaking of chemical bonds between
ions, atoms, molecules or compounds
•
•
Reactants - substances that enter
into a chemical reaction
Products – substance that result
from the chemical reaction
2.2 a Classification of chemical
reactions
- Can be classified as
synthesis, decomposition or
exchange reactions
• Synthesis reactions
o Synthesis reaction - two or
more reactants combine to
form a larger, more
complex
product.
Symbolically presented as;
Example of decomposition reaction;
breakdown of food molecules into basic
building blocks and the breakdown of ATP
to ADP and a phosphate group
•
•
•
Adenosine triphosphate (ATP) – building
blocks obtained the food and the
synthesis; Stands for;
•
•
T stands for tri or three
P stands for a phosphate group
Thus, ATP consists of adenosine and three
phosphate group
•
Anabolism – synthesis reactions
that occur in the body
Synthesis reactions in which water is also
a product are called dehydration (waterout) reactions.
Catabolism
–
decomposition
reaction that occur in the body
collectively
Hydrolysis reaction – reactions that
use water
Metabolism – all of the anabolic
and catabolic reactions in the body
Exchange reactions
-Combination of a decomposition reaction
and a synthesis reaction
-Symbolic representation of an exchange
reaction
Example of an exchange reaction is the
reaction of chloric acid (HCI) with sodium
hydroxide (NaOH) to form table salt
(NaCI) and water (H2O)
Reversible reactions
-Reaction can run in the opposite
direction
-Product converted back to the original
reactants
Decomposition reactions
- Reactants are broken down into smallest,
less complex products
•
Equilibrium – rate of product
formation is equal to the rate of
reactant formation of the reaction
An important reversible reaction in the
human body occurs when carbon dioxide
(CO2) and water (H20) form hydrogen ions
(H+) and bicarbonate ions (HCO-3). The
reversibility of the reaction is indicated
by two arrows pointing in opposite
directions;
•
•
Energy
P is used to represent inorganic
phosphate
As the result of breaking an
existing chemical bonds in food
molecules, new chemical bonds
are formed to create ATP
-Capacity to do work
Energy subdivided into two
1. Kinetic energy – caused by
movement that does a work
2. Potential energy - stored energy
•
•
Work – movement of the matter
The energy is the ability to put
matter into motion
Potential and kinetic energy exist in many
different forms;
1. Mechanical energy
o Energy resulting from the
position or movement of an
object
o Such as;
o Moving limbs
o Breathing
o Circulating blood
o Involve mechanical energy
2. Chemical energy
o Form of potential energy
o Stored within chemical
bonds of a substance
3. Heat energy
4. Electrical energy
5. Electromagnetic
energy
(radiant)
If the potential energy in the reactant is
less than that in the products, energy
input is needed for the reaction to occur.
An example is the synthesis of ATP from
ADP:
Energy and chemical reactions
•
•
The larger sunburst represents
greater potential energy
The smaller sunburst represents
less potential energy
o
o
The input of energy is
required for the synthesis
of ATP
Energy is released as a
result of the breakdown of
ATP
If the potential energy is the reactants is
more than that in the products, energy is
released from this reaction. For example,
the breakdown of ATP releases energy;
•
•
•
The majority of this energy released is
used by cells to do work such as
synthesizing or transporting certain
molecules in the cell, or to do
mechanical work such as contracting
muscles.
Some energy breakdown of ATP is
released as heat
Human
body
temperature
is
maintained by heat produced as a byproduct of chemical reactions
Rate of chemical reactions
- Rate in which a chemical reaction
proceeds are influenced by several factors
•
•
Catalyst – increase the rate of
chemical reaction, without itself being
permanently changed or depleted
Enzyme – protein catalyst that
increase the rate, in which chemical
reactions proceeds, without the
enzymes being permanently changed
Activation energy and enzymes
•
•
•
Activation of energy requires to
initiate chemical reactions
Without enzymes, a chemical
reaction can proceed, but it needs
more energy input
Enzymes lower the activation
energy, making it easier for the
reaction to proceed
Applications of Atomic Particles
•
Protons, neurons and electrons are
responsible for the chemical
properties of atoms
The greater the concentration of the
reactants, the greater the rate at which a
chemical reaction will occur
Molecular
motion
changes
as
environmental temperature change, the
rate of chemical reaction is partially
dependent on temperature
2.3 Acids and Bases
- The body has many molecules and
compounds called acids and bases that
alter the body functions
As the pH value becomes smaller, the
solution becomes more acidic
As the pH value becomes larger, the
solution becomes more basic
1. Acid – proton donor
• Hydrogen atom without electron is
proton
Any substance that releases hydrogen
ions (H+) in water is an acid. For
example, hydrochloric acid (HCl) in the
stomach forms H+ and chloride ions
(Cl −):
2. Base – proton acceptor
For example; sodium hydroxide (NaOH)
forms sodium ions (Na+) and hydroxide
ions (OH-). It is a base because the OH- is
a proton acceptor that binds with a H+ to
form water;
pH Scale
The pH Scale
- Referring to the H+ concentration in a
solution
The normal pH range for human blood is
7.35 to 7.45
- The concentration of H+ determines the
pH value.
Acidosis
•
The scale ranges from 0 to 14
1. Neutral solution – has equal
number of H+ and OH- and thus
pH of 7.0
2. Acidic solution – has greater
concentration of H+ than of OHand does a pH less than 7.0
3. Basic or alkaline solution – has
fewer H+ than OH- and thus a pH
greater than 7.0
•
•
•
If blood pH drops below 7.35
The nervous system is depressed
Individual becomes disoriented
and possibly comatose
Alkalosis
•
•
•
If blood pH rises above 7.45
The nervous system becomes over
excitable
Individual can be extremely
nervous or have convulsions
BOTH ACIDOSIS AND ALKALOSIS CAN
RESULT TO DEATH
Salts
- Compound consisting positive ion other
than H+ and a negative ion other than OH- Salts are formed by the reaction of an
acid and a base
Buffers
•
For example, hydrochloric acid (HCI)
combines with sodium hydroxide (NaOH)
to form the salt sodium chloride (NaCI)
•
•
Buffers
- Chemical behavior of many molecules
changes as the pH of the solution in which
they are dissolved changes
- The survival of the organism is depending
on the ability to maintain homeostasis
- Body fluid pH should be within the
narrow range
- One way to normal body fluid pH
- It can resist changes in pH
Either an acid or a base is added to a
solution containing buffer
The addition of an acid to a no
buffered solution of water results
in increase of H+ that causes large
decrease in pH
The addition of an acid to a
buffered solution results in a much
smaller change in pH
The added H+ bind to the buffer
symbolized by the letter B
2.4 Inorganic Molecules
•
•
Inorganic chemistry
•
•
Deals with substance that do not
contain carbon
It deals with substance that lack
carbon-hydrogen bonds
Water
- Has many unique properties dues to its
polar nature
•
Inorganic substance plays many vital
roles in human anatomy and physiology
1. The O2 we breath
2. The CO2 we exhale
3. The calcium phosphate that makes
our bones
4. The metals required for protein
functions such as iron for O2
transport
Organic chemistry
•
•
Study
of
carbon-containing
substances
With a few exceptions
Oxygen and Carbon Dioxide
Oxygen (O2)
•
•
•
•
Small, nonpolar and inorganic
molecule
Consisting two oxygen atoms
bound together by double covalent
bond
21% of gas in the atmosphere is O2
that is essentials for living
organisms
Human require O2
Carbon dioxide (CO2)
•
•
•
•
Consist of one carbon atom bound
to two oxygen atoms
Produced when food molecules
such as glucose are metabolized
with the cells of the body
Once CO2 is produced it eliminate
the cells as metabolic by-product;
Transferred to the lungs by the
blood
Exhaled during respiration
If CO2 is allowed to accumulate
within cells, it becomes toxic
Water is formed when an atom of
oxygen forms polar covalent bonds
with two atoms of hydrogen
Hydrophilic
•
Molecules attached to the water
Hydrophobic
•
Molecules that lack this attraction
Water polarity and the attraction to other
water molecules that is responsible for
the formation of hydrogen bonds between
adjacent water molecules
Hydrogen properties of water that make
water necessary for life:
1. Water stabilizes body temperature
2. Water protects the body
3. Water is required for many
chemical reactions
2.5 Organic Molecules
- Carbon’s ability to form covalent bonds
with other atoms makes possible the
formation of;
Organic molecules
•
•
•
Large
Diverse
Complicated molecules necessary
for life
Purposes
1. Energy molecules for synthesis of
ATP
2. Structural components on the cell
3. Regulatory molecules
Carbon atoms bound together by covalent
bonds constitute the “backbone” of many
large molecules
Two mechanism allows the formation of
molecules
1. Variation in the length of the
carbon chains
2. Combination of the atoms involved
Four major groups of organic molecules
essentials to living organisms
1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic acid
Carbohydrates
- Organic molecules
- Composed of carbon, hydrogen, oxygen
atoms
Three major roles in the body
1. Parts of other organic molecules
2. Broken down to provide energy
3. Undigested they provide bulk
(fiber) in feces
In most carbohydrates, for each carbon
atom there are two hydrogen atoms and
one oxygen atom
Each molecule called carbohydrates
because each carbon (carbo-) is
combines with the same atoms that
form water (hydrated).
For example, the chemical formula for
glucose is C6H12O6
Monosaccharides
•
simplest carbohydrates or simple
sugars
Building blocks of carbohydrates
Glucose (blood sugar) and fructose
(fruit sugar) are important to
monosaccharide energy source for
many body’s cells
•
•
Cells preferentially
synthesize ATP
use
glucose
to
Disaccharides
•
Formed
when
two
monosaccharides are joined by a
covalent bond
For example, glucose and fructose
combine to form the disaccharide sucrose
(table sugar)
Polysaccharides
•
Consists of long
monosaccharides
Lipids
chains
of
Three important polysaccharides
1. Glycogen or animal starch
• main storage form of glucose in
human
• Serves as ready supply of more
glucose for ATP production
2. Starch
• Stores energy for plants in the
same way as glucose stores energy
for animals
3. Cellulose
Starch and cellulose are two important
polysaccharides found in plants
- Major group of organic molecules
- Relatively insoluble in water
Important functions in body
1. Provide protection and insulation
2. Help regulate many physiological
processes
3. Form membranes
4. Major energy storage molecules
which can be broken down and
used as an energy source
(carbohydrates,
lipids
are
composed mainly of carbon,
hydrogen and oxygen)
Lipids have a lower ratio of oxygen to
carbon than do carbohydrates. This makes
them less polar
The major classes of lipids
1.
2.
3.
4.
Fats which mostly triglycerides
Phospholipids
Eicosanoids
Steroids
Fats
–
molecule
important
energy-storage
Glycerol and fatty acids – building blocks
of fats
Glycerol – 3 carbon molecule with
hydroxyl group
Each carbon atom, and fatty acids consists
of a carbon chain with a carboxyl group
attached at one end
A carboxyl group consists of both an
oxygen atom and hydroxyl group attached
to a carbon atom (-COOH)
•
Responsible for the acidic nature
of the molecule because it releases
H+ into solution
•
Triglycerides
•
•
Most common type of flat
molecules
Have three fatty acids bound to a
glycerol molecule
Fatty acids
•
Different from one another
according to the length and degree
of saturation of their carbon chains
Monounsaturated fats, such as olive and
peanut oils, have one double covalent
bond between carbon atoms.
Polyunsaturated fats, such as safflower,
sunflower, corn and fish oils have two or
more double covalent bonds between
carbon atoms.
Changes makes consumption of
trans fats an even greater factor
than saturated fats in the risk for
cardiovascular disease
Phospholipids
•
•
•
Composed of a polar region.
Containing phosphate and a
nonpolar region.
Consisting two fatty acids chains.
Hydrophilic or water-soluble
•
•
Nonpolar end of a phospholipid is
repelled by water and said to be
hydrophobic or lipid-soluble.
Phospholipids
are
important
structure components of cell
membranes.
It is saturated, if it contains only single
covalent bonds between the carbon
atoms.
The carbon chain is unsaturated, if it has
one or more double covalent bonds.
Phospholipids
Eicosanoids
•
Triglyceride
One glycerol molecule and three fatty
acids are combined to produce a
triglyceride.
Trans fats
•
•
•
•
Unsaturated fats
Chemically altered by the addition
of H atoms
The process makes fat more
saturated
Hence more solid and stable
•
•
Group of important chemicals
derived from fatty acids.
Made in most cells.
Important regulatory molecule.
Example, prostaglandins implicated in
regulating the secretion of some
hormones,
blood
clothing,
some
reproductive functions and many other
processes.
Steroids
•
Lipids that have four ring like
structures.
Cholesterol
•
•
•
Important steroid.
Other steroid molecules
synthesized from it.
Important component of
membrane
are
cell
Steroids derived from cholesterol include
bile salts (lipid digestion), estrogen,
progesterone
and
testosterone
(reproductive hormones)
Anime group – organic acids; carboxyl
group, and a side chain designated by
the symbol R.
There are 20 basic type of amino 20 basic
types of amino acids, which differ in their
R group. Humans can synthesize 12 of
them from simple organic molecules, but
the remaining 8 so-called essential amino
acids must be obtained in the diet.
Steroids
Steroids are four-ringed molecules that
differ from one another according to the
groups attached to the rings. Cholesterol,
the most common steroid, can be
modified to produce other steroids.
Proteins
Have many important functions in the
body
1.
2.
3.
4.
5.
Regulation of body processes
Acting as a transportation system
Providing protection
Helping muscle to contract
Providing structure and energy
All proteins are organic macromolecules
that contain carbon, hydrogen, oxygen,
and nitrogen, bound together by covalent
bonds.
Most protein also contains sulfur and
some
contain
small
amounts
of
phosphorus.
Amino acids – building blocks of proteins
Protein Structure
When a chain of amino acids is formed,
chemical interactions between amino
acids cause the entire chain to fold upon
itself in predictable patterns.
Denaturation – Changed in shape; caused
by abnormally high temperatures or
changes in pH
•
Enzymes
•
•
•
Performs many roles in the body.
Increase the rate of chemical
reactions.
Without
enzymes
being
permanently changed.
The body chemical events are regulated
primarily by mechanisms controlled by
concentration or the activity of
enzymes.
1. Rate at which enzymes are
produced in cells.
2. Whether the enzymes are in an
active or inactive form determines
the rate of each chemical reaction.
Nucleic Acids: DNA and RNA
Nucleic acids
composed of
•
•
•
•
•
are
large
molecules
Carbons
Hydrogen
Oxygen
Nitrogen
Phosphorus
Two types of nucleic acids
1. Deoxyribonucleic acid (DNA)
• Genetic material of cells
• Contains
genes
which
determine the structure of
proteins
2. Ribonucleic acid (RNA)
• Structurally related to DNA
• Important
in
protein
synthesis
Nucleotides
•
•
Building blocks of DNA and RNA
Basis are thymine
Composed of;
1. Monosaccharide
2. Nitrogenous base
3. Phosphate group
Monosaccharide is deoxyribose for DNA,
and ribose for RNA
•
•
DNA has two strands of nucleotides
joined together to form a ladder
like structured called double
helix.
The sides of latter formed by
covalent bonds between the
monosaccharides and phosphate
groups of adjacent nucleotides
Each nucleotides of DNA contains
one of the nitrogenous bases;
o Adenine
o Thymine
o Cytosine
o Guanine
The sequence of organic bases in DNA
molecules stores information used to
determine the structures and function of
cells.
A sequence of DNA bases that directs the
synthesis of proteins or RNA molecules is
called a gene.
RNA has a structure similar to a single
strand of DNA.
DNA four different nucleotides make up
the RNA molecule
Uracil can bind only to adenine
Adenosine Triphosphate (ATP)
•
•
•
Most important molecule for
storing and providing energy in all
living organisms
Often called the energy of
currency of cells
Maintained within a narrow of
values, and essentially all energyrequiring chemical reactions stop
when the quantity of ATP become
inadequate.
ATP consist of;
1. Adenosine (a monosaccharide with
adenine)
2. Three phosphate groups
High-energy
•
The second and third phosphate
bonds
Adenosine diphosphate (ADP)
•
Removal of the third phosphate
group
CHAPTER 3
Cell Structures and Their Functions
3.1 Cell Structure
Cells
•
•
•
•
•
Determine the form and function
of the human body.
Basic living unit of all organisms.
Simplest organism consists of
single cells.
Whereas humans are composed of
multiple cells.
Each cell is highly organized unit.
Organelles
•
•
•
Specialized structure.
Perform specific function.
Nucleus is an organelle containing
the cell’s genetic material.
Cytoplasm
•
•
Living material surrounding the
nucleus.
Enclosed by the cell membrane or
plasma membrane.
Organelles and Their Locations and
Functions
The number and type of organelles
within each cell determine the cell’s
specific structure and functions.
3.2 Functions of the Cell
Cell – the smallest units of life
Four important functions performed by
our body cells:
1. Cell metabolism and energy use
• Chemical reactions occur
within cells are
collectively called
metabolism.
• Energy release during
metabolism is used for cell
activities;
o Synthesis of new
molecule
o Muscle contraction
o Heat production
That helps maintain body temperature
2. Synthesis of molecules
• Cell synthesize various type
of molecules
o Proteins
o Nucleic acids
o Lipids
The different cells of the body do not all
produce the same molecules. Therefore,
a cell’s structural and functional
characteristics are determined by the
types of molecules the cell produces
3. Communication
• Cells produce and receive
chemical and
• Electrical signal that allow
to communicate with one
another
For example, nerve cells communicate
with one another and with muscle cells,
causing muscle cells to contract.
4. Reproduction and inheritance
• Each cells contains a copy
of the genetic information
of the individual.
• Specialized cells (sperm
cell and oocytes) transmit
that genetic information to
the next generation.
Nonpolar
3.3 Cell Membrane
•
Cell membrane or plasma membrane
•
•
•
•
Outermost component of a cell.
Encloses the cytoplasm
Forms boundary between material
inside the cell and material
outside it.
Extracellular
•
Substances outside the cell
Cytoplasmic or intracellular
•
Substance inside the cell
Other functions of cell membrane
1. Supporting the cell contents.
2. Acting as a selective barrier that
determines what move into and
out of the cell.
3. Playing a role in communication
between cells.
Two major type of cell membrane
1. Phospholipids
2. Proteins
In addition
3. Cholesterol
4. Carbohydrates
Fluid-mosaic model
•
Arrangement of molecules in the
cell membrane have given rise to
a model of its structure.
The phospholipids form a double layer of
molecules
Polar
•
•
Phosphate-containing ends of the
phospholipids are hydrophilic
(water-loving).
Face the extracellular fluid and
cytoplasm of the cell.
Fatty acid ends of the
phospholipids are hydrophobic
(water-fearing).
Face away from the fluid on
either side of the membrane,
toward the center of the double
layer of phospholipids.
The double layer of phospholipids forms
a liquid barrier between the inside and
outside of the cell.
The double layer of phospholipids has a
fluid quality.
Cholesterol within the phospholipid
membrane gives it added strength and
stability by limiting how much the
phospholipids can move.
3.4 Movement Through the Cell
Membrane
Cell membranes
•
•
Selectively permeable.
They allow some substance, but
not others, to pass into or out of
the cell.
Cytoplasmic
•
•
•
Material has a different
composition than extracellular
material
Cell’s survival depends on
maintaining the difference.
Substance such as
o Enzymes
o Glycogen
o Potassium ions
That can be found in greater
concentration inside the cell
Active
•
Requires the cell to expend
energy, usually form of ATP.
Passive membrane transport
mechanisms include:
1. Diffusion
2. Osmosis
3. Facilitated diffusion
Active membrane transport mechanism
includes:
1.
2.
3.
4.
Active transport
Secondary active transport
Endocytosis
Exocytosis
Diffusion
•
•
Both cytoplasm and extracellular
fluid are solutions.
Each solute tends to move from
an area where it is in higher
concentration to an area where it
is in lower concentration in
solution
For example, gradual spread of salt
throughout a beaker of still water
Cell Membrane
Fluid mosaic model of the cell membrane
•
Composed of a bilayer of
phospholipids and cholesterol
with proteins “floating”.
Passive Membrane Transport
•
Movement through the cell
membrane maybe passive or
active.
Passive
•
Membrane transport does not
require the cell to expend energy
Diffusion
1. When a salt crystal is placed into
a beaker of water, a
concentration gradient exists
between the salt from the salt
crystal and the water that
surrounds it.
2. Salt ions move down their
concentration gradient into the
water.
3. Salt ions and water molecules are
distributed evenly throughout t
Solution
•
Composed of two major parts,
solutes and solvents.
Solute are substances dissolved in a
predominant liquid or gas which is called
solvent
Solutes
•
Concentration gradient
•
To solutes and a concentration gradient
for water exits across the cell membrane.
•
Such as ions or molecules are in
constant motion
Diffusion results from the natural,
constant random motion of all solutes in
a solution.
•
•
Steeper when the concentration
difference is large and/or the
distance is small.
Difference in the concentration of
a solute in a solvent between two
points divided by the distance
between the two points.
In the body, diffusion is an important
means of transporting substances
through the extracellular fluid and
cytoplasm.
movement can disrupt normal cell
functions.
Occurs when cell membranes are;
o Less permeable
o Selectively permeable
o Not permeable
•
•
•
•
The ability to depicts the
direction of water movement is
depending on knowing which
solutions on either side of the
membrane.
The concentration of a solution, is
expressed not in terms of water.
But in terms or solute
concentration.
An easy way to remember the
direction of water movement is
“water follows solutes”.
Water moves to the area with the
greater solute concentration.
Osmotic pressure
•
Force required to prevent
movement of water across a
selectively permeable membrane.
In addition, substances, such as nutrients
and some waste products, can diffuse
into and out of the cell.
Osmosis
•
•
•
Solvent of a solution is also
composed of molecules that are in
constant random motion.
solvent of a solution is also
composed of molecules that are in
constant random motion such as;
o Cell membrane.
o Region of higher water
concentration to one of
lower water concentration.
Important to cells; large volume
changes cause by water
Osmosis
Water moves from the beaker across the
selectively permeable membrane into a
tube containing a solution with a higher
salt concentration.
1. Osmotic pressure can be measured
by placing a solution into a tube
that is closed at one end by a
selectively permeable membrane
and immersing the tube in distilled
water.
2. Water molecules move by osmosis
through the membrane into the
tube, forcing the solution to move
up the tube.
3. As the solution rises, the weight of
the solution produces hydrostatic
pressure, which pushes water out
of the tube back into the distilled
water surrounding the tube.
Hypotonic
•
Concentration gradient between
the solution and the cell’s
cytoplasm.
Isotonic
•
Solution, the concentrations of
various solutes and water are the
same on both sides of the cell
membrane.
In general, solutions injected into blood
vessels or into tissues must be isotonic
to the body’s cells because swelling or
shrinking disrupts normal cell function
and can lead to cell death.
Effects pf Hypotonic, Isotonic, and
Hypertonic Solutions on Red Blood Cells
The shape of a cell may change when it
is placed in a new solution.
Facilitated diffusion
-
Lysis - If the cell swells enough, it can
rupture.
The cell therefore neither shrinks nor
swells.
Hypertonic
•
Solutes and a lower concentration
of water relative to be cytoplasm
of the cell.
When the cells immersed in a hypertonic
solution, water moves by osmosis from
the cell into the hypertonic solution,
resulting a cell shrinkage or crenation.
-
The phospholipid bilayer
acts as a barrier to most
water-soluble substances
though certain small, water
soluble substances can
diffuse
between
the
phospholipids molecules of
cell membrane.
Is a mediated transport
process,
involving
membrane proteins such as
channel or carrier proteins,
to move substance across
the cell membrane.
1. Leak channels – constantly allow
ions to pass through.
2. Gated channels – limit the
movement of ions across the
membrane by opening and closing.
Facilitated Diffusion
The carrier molecules transport glucose
across the cell membrane from an area
of higher glucose concentration (outside
the cell) to an area of lower glucose
concentration (inside the cell)
The transport of glucose into most cells
occurs by facilitated diffusion
•
•
Diffusion only occur from a higher
to a lower concentration.
Glucose cannot accumulate within
these cells at a higher
concentration than exists outside
the cell.
Channel
•
•
Diffuses across the cell membrane
by passing through cell membrane.
Or through carrier molecules.
Cell membrane channels consist of large
molecules that extend from one surface
of cell membrane to the other.
The characteristics of ion or molecules is
determining whether it can pass through
a channel.
Two channels of membrane
Diffusion Through the Cell Membrane
Non-lipid-soluble molecules (small red)
diffuse through membrane channels.
Lipid-soluble molecules (orange) diffuse
directly through the cell membrane.
Carrier molecules
•
•
•
Proteins within the cell membrane
Involved in facilitated diffusion
Can move water-soluble molecules
or electrically charged ions across
the cell membrane.
1. A molecule to be transported binds
to a specific carrier molecule on
one side of the membrane.
2. binding of the molecule to the
carrier molecule in the cell
membrane. Causes the three-
dimensional shape of the carrier
molecule to change, and the
transported molecule is moved to
the opposite side of the cell
membrane.
Active Membrane Transport
Active Transport
•
•
Active transport requires energy in the
form of ATP
Leak and Gated Membrane
Channels
K+ leak channel (purple) is always open,
allowing k+ to diffuse across the cell
membrane.
The gated Na+ channel (pink) regulates
the movement of Na+ across the
membrane by opening and closing.
The transported molecule is then released
by the carrier molecule. Which resumes
its original shape and s available to
transport another molecule.
If ATP is not available, active transport
stops.
Cystic fibrosis
•
•
•
•
•
Specificity
•
•
Similar to channel
Only specific molecules
transported by the carriers
Utilizes membrane proteins to
move substance across the cell
membrane.
o From higher concentration
against
concentration
gradient.
Processes accumulate substances
on one side of the cell membrane
at concentration many times
greater than those on the other
side.
Genetic disorder.
Affects the active transport of CIinto cells.
Occurs at a rate of approximately
mately 1 per 2000 births.
Currently affected 33,000 people
in the United States.
Results an abnormality in CI
channels.
are
Carrier molecule are commonly identified
by the specific substance they transport.
For example, glucose carrier molecules
move glucose across the membrane.
Active transport: Sodium-Potassium
Pump
The sodium-potassium pump requires
ATP to move Na+ out of the cell and k+
into the cell.
In some cases, the active transport
mechanism can exchange one substance
for another
Cotransport
For example, the sodium-potassium pump
moves Na+ out of cells and K+ into cells.
The result is higher concentration of Na+
outside the cell and a higher
concentration of k+ inside the cell.
Counter transport
•
•
Diffusing substance moves in
the same directions as a
transported substance.
Diffusing substance moves in
a direction opposite to that
transported substance.
Endocytosis and Exocytosis
Secondary Active Transport
•
•
Involves the active transport of one
substance.
Such as Na+; establishing a
concentration gradient.
o Provides energy for moving
a second substance across
the membrane.
Vesicles
•
•
Transported across the cell
membrane in membranebound sacs.
Vesicles and cell membrane
can fuse because of the fluid;
allows vesicles the move
across the cell membrane.
Endocytosis
•
•
•
Uptake of material.
Formation of vesicles.
Exhibits specifically, through
the process of receptormediated endocytosis.
Secondary Active Transport
The active transport of Na+ out of the
cell (Step 1) maintain a Na+
concentration gradient, which provides
the energy for moving glucose against
its concentration gradient (step 2)
1. A Na + -K + pump actively moves
Na + out of the cell, maintaining
a higher concentration of Na +
outside of the cell compared to
the cytoplasm.
2. The diffusion of Na + down its
concentration gradient provides
the energy to transport a second
substance, in this example
glucose, across the cell
membrane.
Receptor-Mediated Endocytosis
Molecules bind to receptors on the cell
membrane, and a vesicle forms to
transport the molecules into the cell.
1. The cell membrane contains
specific receptor molecules that
bind to certain molecules.
2. When the specific molecules bind
to the receptors, endocytosis is
triggered. A vesicle begins to
form, bringing the receptors and
the bound molecules into the cell.
3. The vesicle forms completely in
the cytoplasm as its membrane
separates from the cell
membrane.
Phagocytosis
•
•
Important to white blood cells
Take up and destroy harmful
substances that enter the body
Pinocytosis
•
•
•
Distinguished from phagocytosis.
Much smaller vesicles are formed.
Contain liquid rather than solid
particles.
Exocytosis
•
Release of substance from cell
through fusion of a vesicle with
the cell membrane.
Exocytosis
(a)
Diagram
of
exocytosis
(b)
Transmission of electrons micrograph
of exocytosis
1. Membrane-bound sac called a
secretory vesicle accumulates
materials for release from the cell.
2. The secretory vesicle moves to the
cell membrane, where the vesicle
membrane fuses with the cell
membrane.
3. The material in the vesicle is
released from the cell. Examples
of exocytosis are the secretion of
digestive enzymes by the pancreas
and the secretion of mucus by the
salivary glands.
Endocytosis results in the uptake of
materials by cells, and exocytosis
allows the release of materials from
cells.
Transcytosis
•
•
Endothelial cells of blood
capillaries, material is moved
through cells.
Substance takes into the cell by
endocytosis, in the vesicles is
moved across the cell and the
substance is then release from the
cell by exocytosis.
Both endocytosis and exocytosis
require energy in the form of ATP for
the formation and movement of
vesicles.
3.5 Organelles
Chromosomes
•
Nucleus
•
•
•
Large organelle within the cell
All cell bodies have nucleus at
some point in their life cycle
through some cells.
Skeletal muscle cells, contains
more than one nucleus.
Nuclear envelope
•
•
Contents of nucleus is separated
from the rest of cytoplasm.
Consists of an outer membrane
and an inner membrane with a
narrow space between them.
23 pairs
o Consist of DNA and
proteins
Chromatin
•
During most of cell’s life;
chromosomes are loosely coiled
and collectively.
When a cell prepares to divide, the
chromosomes become tightly coiled and
are visible when viewed with a
microscope.
Nuclear pores
•
•
Inner and outlet membranes come
together.
Passes through which materials
can move into or out of the
nucleus.
Structure of a Chromosome
Nucleus
(a) The nuclear env elope consists of
inner and outer m em branes, which
becom e fused at the nuclear pores. The
nucleolus is a condensed region of the
nucleus not bounded by a m em brane
and consisting m ostly of RNA and
protein. (b) Transm ission electron m
icrograph of the nucleus. (c) Scanning
electron m icrograph showing the m em
branes of the nuclear env elope and the
nuclear pores.
Chromosomes consist of DNA and
proteins. When loosely coiled,
chromosomes are collectively referred
to as individual structures.
Nucleoli
•
•
Diffuse bodies with no surrounding
membrane that are found within
the nucleus.
Usually one several nucleoli within
the nucleus.
Endoplasmic reticulum
•
Series of membranes forming sacs
and tubules that extends from the;
o Outer nuclear membrane
into cytoplasm.
Rough ER
•
•
Production of Ribosomes
Ribosomal subunits are produced in the
nucleus and then move into the
cytoplasm, where are they from
ribosomes during protein synthesis.
1. Proteins produced in the cytoplasm
move through the nuclear pores
into the nucleus and to the
nucleolus.
2. These proteins are joined to
ribosomal ribonucleic (RYE-bohnooKLEE-ik) acid (rRNA), produced
within the nucleolus, to form large
and small ribosomal subunits.
3. The ribosomal subunits then move
through the nuclear pores of the
nuclear
envelope
into
the
cytoplasm.
4. In the cytoplasm, one large and
one small subunit join to form a
ribosome during protein synthesis.
Ribosomes
•
•
The organelles where proteins
are produced.
May be attached to other
organelles.
o Endoplasmic reticulum.
With attached ribosomes.
Large amount of rough ER in a cell
indicates that it synthesizing large
amount of protein for export from
the cell.
Smooth ER
•
•
Without attached ribosomes.
Site for lipid synthesis and
participates in detoxification of
chemical within cells.
In skeletal muscles, the smooth ER stores
calcium ions (Ca2+)
Endoplasmic Reticulum
(a) The endoplasmic reticulum is
continuous with the nuclear envelope
and can exist as either rough
endoplasmic reticulum (with ribosomes)
or smooth endoplasmic reticulum
(without ribosomes). (b) Transmission
electron micrograph of the rough
endoplasmic reticulum.
Free ribosomes
•
Ribosomes are not attached to any
other organelle.
Rough and Smooth Endoplasmic
Reticulum
Golgi Apparatus
•
•
•
Called Golgi complex.
Closely packed stacks of;
o Curved
o Membraned-bound sacs
It collects;
o Modifies
o Packages
o Distributes proteins
o Lipids manufactured by the
ER
Lysosomes
•
•
Membraned-bound vesicles formed
from the Golgi apparatus.
Contained a variety of enzymes
that function as intracellular
digestive systems.
For example, proteins produced at the
ribosomes enter the Golgi apparatus from
the ER.
Action of Lysosomes
Digestive enzymes in lysosomes are
used to breakdown substances.
Golgi Apparatus
(a) The Golgi apparatus is com posed of
flattened, membranous sacs and
resembles a stack of dinner plates or
pancakes. (b) Transmission electron
micrograph of the Golgi apparatus.
Secretory Vesicles
•
•
•
•
Described in “Endocytosis and
Exocytosis”.
A vesicle is small membranebound sac that transport or stores
materials within cells.
Pinch off from the Golgi apparatus
and move to the cell membrane.
Accumulate in the cytoplasm and
are released to the exterior when
the cell receives a signal.
Lysosomes and Peroxisomes
1. Extracellular material is brought
into the cell as a vesicle forms
around the material.
2. A lysosome forms at the Golgi
apparatus.
3. The lysosome moves through the
cytoplasm to the vesicle and fuses
with it. The enzymes in the
lysosome are released into the
vesicle.
4. The lysosomal enzymes mix with
the material in the vesicle, and the
material is broken down.
The process is seen when white blood cells
phagocytize bacteria.
The enzymes within lysosomes destroy the
phagocytized bacteria.
Pompe Disease
•
Caused by the inability of
lysosomal enzymes to breakdown
the
carbohydrate
glycogen
produces in certain cell.
Peroxisomes
•
•
Small membraned-bound vesicles
Containing
enzymes
that
breakdown;
o Fatty acids
o Amino acids – breakdown
can be toxic to a cell
o Hydrogen peroxide – by
product of fatty acid
Enzymes in peroxisomes break down by
hydrogen peroxide to water and O2.
Cells active in detoxification such as liver
and kidney cells, have many peroxisomes.
Mitochondria
•
Small organelles with inner and
outer membranes separated by
space.
o Outer membrane – smooth
contour.
o Inner membrane – number
of folds called cristae.
▪ Which project into
the
interior
of
mitochondria.
Mitochondrial matrix
•
Materials
within
membrane
the
Mitochondrion
(a) Typical mitochondrion structure. (b)
Transmission electron micrograph of
mitochondria in longitudinal and cross
sections.
ATP is the main energy source for most
chemical reactions within the cell.
Cells with a large energy requirement
therefore have more mitochondria than
cells that require less energy.
Muscle cells also require large number of
ATP for contraction.
Cytoskeleton
•
•
Internal framework of the cell.
Contains protein structures that
support the cell.
Protein structures;
1. Microtubules
2. Microfilaments
3. Intermediate filament
inner
Mitochondrial DNA (mtDNA)
•
Contains enzymes
Mitochondria are the major sites of
adenosine
triphosphate
(ATP)
production within cells.
Mitochondria
respiration.
carry
out
aerobic
Cytoskeleton
(a) Diagram of the cytoskeleton. (b)
Scanning electron micrograph of the
cytoskeleton.
Microtubules
•
•
•
Hollow structure formed from
protein subunits.
Perform a variety of roles;
o Helping to support the
cytoplasm of the cell.
o Assisting cell division.
o Forming
essential
components of certain
organelles.
▪ Cilia and flagella.
Extending from the centrosome,
play an important role in cell
division, as we will learn in
“mitosis”
Microfilaments
•
•
•
•
Small fibrils
Formed from protein subunits that
structurally support the cytoplasm.
Determining cell shape.
Some microfilaments involved with
cell movement.
Centriole
a) Structure of a centriole, which is com
posed of nine triplets of microtubules.
Each triplet contains one complete
microtubule fused to two incomplete
microtubules. (b) Transmission electron
micrograph of a pair of centrioles,
which are norm ally located together
near the nucleus. One is shown in cross
section and one in longitudinal section
Cilia, Flagella and Microvilli
Cilia
•
•
Intermediate filaments
•
•
Fibrils formed from protein
subunits that are smaller in
diameter than microtubules.
Provides mechanical support to the
cell.
o Keratin – specific type of
intermediate filament
▪ Protein associated
with skin cells.
Centrioles
•
•
•
•
Specialized area of cytoplasm
Closed to the nucleus where
microtubules formation occurs.
It contains two centrioles
Each centriole is small; cylindrical
organelle
composed
of
microtubules organized into nine
triplets.
o Each triplet consists three
parallel
microtubules
joined together.
•
•
•
•
Project from the surface of cells.
Vary in number from none to
thousands per cell and are capable
in moving.
Cylindrical structures that extend
from the cell.
Composed of microtubules.
Organized similar to centrioles
which are enclosed to by the cell
membrane.
Cilia are numerous on surface cells
that line the respiratory tract.
Flagella
•
•
Structure similar to cilia but are
much longer.
Occurs only one per cell.
Sperm cells each have one flagellum,
which propels the sperm cell.
Microvilli
•
Specialized extensions of the cell
membrane that are supported by
microfilaments.
•
Numerous on cells that have them
and they increase of the surface
area of those cells.
3.6 Whole-cell Activity
•
•
Cells characteristics are ultimately
determined by the type of proteins
it produces.
In order to understand how a cell
functions, we must consider:
o The relationship between
genes and proteins.
For example, the transport of many food
molecules into the cell requires cell
membrane proteins.
Proteins such as transport proteins and
enzymes.
Information contained DNA within the
nucleus determines which type and in
what sequence amino acids are combine
at ribosomes to form proteins.
The human body is composed of trillions
of cells.
Each human begins life as a single cell.
Gene Expression
•
•
Process by which information
stored in the genes of DNA.
Molecules directs the manufacture
of the various proteins in our cells.
DNA molecule consist of nucleotides
joined together to form two nucleotide
strands.
Genes
•
•
•
•
Two strands are connected and
resemble a ladder that is twisted
around its long axis’s.
Section of DNA.
Sequence of nucleotides that
provide a chemical set of
instructions for making specific
protein.
Gene is a recipe in creating
protein.
Overview of Gene Expression
Gene expression involves two steps:
transcription, which occurs in the
nucleus, and translation, which occurs
in the cytoplasm.
Two steps of gene expression
1. Transcription
• Occurs in the nucleus.
• Information stored in a
region of the DNA.
• Used
to
produce
a
complementary
RNA
Molecule called messenger
RNA (mRNA).
2. mRNA molecule
• Moves to ribosomes in the
cytoplasm
where
translation occurs.
• Nucleotide sequence of the
molecule
is
used
to
determines
the
composition
of
a
polypeptide chain.
• A precursor to a protein.
Translation
•
Changing of something from one
form to another.
In terms of analogy: DNA contains many
genes for making different proteins.
DNA however, is too large a molecule to
pass through the nuclear pores to the
ribosomes, where proteins are made.
DNA remains in the nucleus. Therefore,
through transcription, the cell makes an
RNA molecule, copy of the gene necessary
to make a particular protein.
mRNA travels from the nucleus to
ribosomes in the cytoplasm, where
information in the copy is used
construct a protein by means
translation.
the
the
to
of
Amino acids
•
The necessary ingredient
synthesize a protein
to
Transfer RNAs (tRNAs)
•
Carry the amino acids to the
ribosome.
Gene expression involves transcription
(making a copy of a gene) and
translation (converting the copied
information into a protein).
Transcription
•
•
First step in gene expression.
Takes place in the nucleus of the
cell.
Formation of mRNa by
Transcription of DNA
1. DNA determines the structure of
mRNA
through
transcription.
During transcription, the double
strands of a DNA segment
separate.
2. DNA nucleotides of the gene pair
with RNA nucleotides that form
the mRNA. Each nucleotide of DNA
contains one of the following
organic bases: thymine, adenine,
cytosine,
or
guanine;
each
nucleotide of mRNA contains
uracil, adenine, cytosine, or
guanine.
3. After the DNA nucleotides pair up
with the RNA nucleotides, an
enzyme catalyzes reactions that
form chemical bonds between the
RNA nucleotides to form a long
mRNA segment. Once the mRNA
segment has been transcribed,
portions of the mRNA molecule
may be removed.
Genetic Code
•
Protein synthesis relies on the
cell’s ability to “decode” the
information stored in the
nucleotide sequence of the mRNA
produced during translation.
Codons
•
•
The information in mRNA is
carried in groups of three
nucleotides.
Each codon specifies a particular
amino acid.
For example, the nucleotide sequence
uracil, cytosine, and adenine (UCA)
specifies the amino acid serine. There are
64 possible mRNA codons, but only 20
amino acids. As a result, more than 1
codon can specify the same amino acid.
For example, CGA, CGG, CGU, and CGC
code for the amino acid arginine. Some
codons do not specify a particular amino
acid but perform other functions.
•
Between amino acids bound to the
tRNAs.
Polypeptide chain
•
•
Ribosomes moves down the mRNA
one codon at a time.
Releasing one of the tRNA and
allowing the next tRNA to move
into position.
A protein can consist of a single
polypeptide chain or two or more
polypeptide chains that are joined after
each chain is produced on a separate
ribosome.
Cell Cycle
•
During
the
growth
and
development, cell divisions allows
for a dramatic increase in cell
number after fertilization of an
oocyte.
For example, UAA does not code for an
amino acid; instead it acts as a signal to
end the translation process and therefore
is called a stop codon.
Translation
•
•
•
Synthesis of proteins based on the
information in mRNA.
Occurs in ribosomes.
mRNA molecules produced by
transcription pass through nuclear
pores to the ribosomes.
mRNA process of translation requires two
other types of RNA: tRNA and ribosomal
RNA (rRNA).
There is one type of tRNA for each mRNA
codon.
Peptide bond
•
Enzymes associated with the
ribosome causes the formation
Cell Cycle
The cell cycle is divided into interphase
and
cell
division
(mitosis
and
cytokinesis). Interphase is divided into
G1, S, and G2 sub-phases. During the G1
phase, the cell carries out routine
metabolic activities. During the S
phase, DNA is replicated. During the G2
phase, the cell prepares for division. (a)
Following mitosis, two cells are formed
as the cytoplasm divides. Each new cell
begins a new cell cycle. (b) Many cells
exit the cell cycle and enter the G0
phase, where they remain until
stimulated to div ide, at which point
they reenter the cell cycle.
During interphase, DNA replication
occurs, producing two copies of each
chromosome. During mitosis, a cell
divides, producing two new cells, each
containing
a
complete
set
of
chromosomes.
Two major phases
Cell division
1. Nondiving
interphase.
2. Cell divisioin.
phase
called
A cell spends most of its life cycle in
interphase
performing
its
normal
functions.
Three phases of interphase
1. G1 phase – during which the cell
carries out normal metabolic
activity.
2. S phase – during which the DNA is
replicated.
3. G2 phase – during which the cell
prepares to divide.
At the end of interphase, the cell has two
complete sets of genetic material.
•
•
•
Formation of daughter cells from a
single parent cell.
The new cells necessary for growth
and tissue repair are formed
through mitosis.
Reproductive cells are formed
through meiosis.
Diploid
•
•
•
Each of the body cells.
Except for reproductive cells.
Number of chromosomes which for
human is 46.
Reproductive cells have the haploid
number of chromosomes, which is half the
diploid number of chromosomes.
The 23 pairs, 1 pair is the sex
chromosomes, which consist of 2 X
chromosomes if the person is a female or
an X chromosome and a Y chromosome if
the person is a male. The remaining 22
pairs of chromosomes are called
autosomes.
Mitosis
•
A parent cell divides to from two
daughter cells with the same
amount and type of DNA as the
parent cell.
Four stages of mitosis
1.
2.
3.
4.
Cell Cycle
Prophase
Metaphase
Anaphase
Telophase
Recall the during the S phase
interphase, the DNA is replicated.
of
Each chromosome is composed of two
genetically
identical
strands
of
chromatin called chromatids.
Which are linked by a specialized region
called centromere.
1. Interphase
• DNA exists as thin threads of
chromatin. During the S phase of
interphase, DNA molecules are
replicated.
2. Prophase
• Chromatin condenses to form
visible
chromosomes
each
composed of the two chromatids.
• Microtubules called spindle fibers
extend from the centrioles.
3. Metaphase
• Chromosomes align near the center
of the cell.
• The
movement
of
the
chromosomes is regulated by the
attached spindle fibers.
4. Anaphase
• At the beginning chromatids
separate.
• When
this
happens,
each
chromatid is then called a
chromosome.
• At this point two identical sets of
46 chromosomes are present in the
cell.
• Each set of chromosomes has
reached an opposite pole of the
cell, and the cytoplasm begins to
divide.
5. Telophase
• The chromosomes in each of the
daughter cells become organized
to form two separate nuclei, one in
each newly formed daughter cell.
• The chromosomes begin to unravel
and resemble the genetic material
during interphase.
6. Mitosis is complete
Following telophase, cytoplasm
division is completed, and two
separate daughter
produced.
cells
are
Differentiation
•
•
•
•
•
A sperm cell and an oocyte unite to
form a single cell, and a new
individual begins.
The single cell formed during
fertilization divides by mitosis to
form two cells, which divide to
form four cells, and so on.
The process by which cells develop
with specialized structures and
functions.
During differentiation of a cell,
some portions of DNA are active,
but others are inactive.
The active and inactive sections of
DNA differ with each cell type.
For example, the portion of DNA
responsible for the structure and function
of a bone cell is different from that
responsible for the structure and function
of a muscle cell.
Diversity of Cell Types
The cells of the hum an body show great
diversity in appearance and function.
Cancer
•
•
•
•
Refers to a malignant, spreading
tumor and the illness that results
from it.
Tumor – abnormal mass of tissue.
Cancers lack the normal growth
control that is exhibited by most
other adult tissues.
Cancer results when a cell or group
of cells breaks away from the
normal control of growth and
differentiation.
Two types of Tumor
1. Malignant
• With malice
• Caused of harm
• Malignant
tumors
can
spread by local growth and
expansion or by metastasis.
2. Benign
• Less
dangerous
than
malignant ones.
• Benign tumor enlarges, it
can compress surrounding
tissues and impair their
functions.
Apoptosis
•
•
•
•
•
•
Programmed cell death.
Apoptosis regulates the number
of cells within various tissues of
the body.
Normal process by which cell
numbers within various tissues are
adjusted and controlled.
Apoptosis removes extra tissue,
such as cells between the
developing fingers and toes.
Apoptosis is regulated by specific
genes.
As apoptosis begins, the chromatin
within the nucleus condenses and
fragments.