BIOLOGY
SUMMARY
ALL
CHAPTERS
1-10
Marvel Orahin
A visually reorganized summary with no
watermarks
BIOLOGY
Grade 12 2021-2022
Table of contents
Chapter 1………………………………………2
Chapter 2………………………………………14
Chapter 3………………………………………27
Chapter 4………………………………………39
Chapter 5………………………………………53
Chapter 6………………………………………63
Chapter 7………………………………………75
Chapter 8………………………………………83
Chapter 9………………………………………95
Chapter 10………………………………………108
1
Section 1.1: The Human Body Plan
Levels of organization:
Cell  Tissue  Organ  Organ system  Body
What is a tissue?
A collection of cells similar in structure that perfom the same function.
Types of tissue:
Muscle: composed of cells (muscle fibers)
that can contract
• Smooth: Involuntary movement of substances throughout the body
• Skeletal: Attached to the skeleton; movement of bones
• Cardiac: Pumps blood (heart)
Nervous: contains cells (neurons) that can
recieve and transmit electrical signals
• Sense changes, interpret sensory information, coordination of
voluntary and involuntary acitivities.
Epithelial: Lines and covers internal and
external surfaces
•
•
•
•
Various thickness and arrangements
Tightly bound
Dead layer of skin
Single layer of flattened cells in blood vessels
Connective: Binds, supports, and protects
structures
•
•
•
•
Instracellular substance called matrix
Solid matrix: Bone
Semi-solid matrix: Fat, Cartilage, Tendons, Ligaments
Liquid matrix: Blood (plasma)
2
Organs and integration
What is an organ?
Consists of various tissues that work together to carry out a specific function .
Stomach
 Has all four types of tissues
 Part of the digestive system
 Works with the small intestine, liver, pancreas
Organs work together and are all integrated on some level with
boundaries that are not well-defined.
Pancreas
 Main function is digestion (secretion of digestive juices)
 Also secretes endocrine hormones (insulin & glucagon)
The cardiovascular systems transports the nutrients and oxygen generated by the
digestive and respiratory systems respectively.
Body cavities
There are certain compartments in the human body that house and protect
organs.
Cranial
Contains the Brain
Thoracic
Lungs, Esophagus, Sternum, Ribs, Heart,
Thymus...
Abdominal
Ovaries, Kidneys, Intestines,
Stomach...(digestive etc.)
Spinal
Contains the spinal cord
Pelvic
Organs of the reproductive and excretory
systems (not all of them)
3
Section 1.2: The Skeletal System
The Skeleton
 Appendicular
o The bones of the skull, ribs,
spine, and sternum
 Axial
o The bones of the arms and
legs, along with the scapula,
clavicle, and pelvis
 There are 206 bones in the body
 Making up <20% of the body’s mass
Function and Structure
 Bones provide a rigid framework against
which muscles can pull
 Give shape and structure to the body
 Support and protect delicate internal
 ὀστέον (ostéon, “bone”)
o Osteo- (prefix relating to bone)
 Osteocytes
o The basic bone cell, embedded
within the gaps between protein
organs
 Store minerals, such as calcium and
phosphorus,
 Production of R.B.C’s, Platelets, and
some types of W.B.C.’s
 Moist, living tissues (not dry and rigid)
layers. Surrounded by a hard,
crystalline matrix containing
calcium.
4
Long Bone Structure
Periosteum
• A tough membrane that covers the bone surface,
supplying nutrients & nerves that signal pain
Compact bone
• A hard material, composed of mineral crystals &
protein fiber cylinders (lamellae), that allows
bone to endure large amounts of stress. Right
below the periosteum
Haversian canals
• Narrow channels concentric with lamellae that
house bloods vessels; delivering nourishment to
bone tissue
Spongy bone
• Beneath compact bone
• Connective tissue
• Lattice work structure (light & strong)
• Contains Red bone marrow
Bone marrow:
 Red bone marrow
o Found in [Spongy bone, ends of long bones, sternum, ribs,
vertebrae, pelvis]
o Produces R.B.C’s, Platelets, and W.B.C’s (not all though)
 Yellow bone marrow
o Found in [Shafts of long bone]
o Largely exists as a fat cells acting as an energy reserve
o Can turn into R. bone marrow if severe blood loss occurs.
*If an injury to the bone is sustained it is called a fracture (cracks or breaks).
Fractures heal as long as circulation to the periosteum is maintained.
5
Bone Development
Ossification: The formation of bone from cartilage by osteocytes as a result
of mineral deposition during fetal development and adolescence.
 Fetal ossification
o During the 2nd month, much of the skeleton is made of cartilage
o
During the 3rd month, osteocytes begin to release and lodge
mineral in between the spaces between cartilage cells.
o
Does all cartilage turn to bone?

o
No, some remains to lend flexibility to parts of the body
[ears, nose, areas between nose, along the inside of trachea]
Is all bone ossified cartilage?

No, some bones directly form from fused osteocytes
originally scattered randomly throughout the embryonic
connective tissue. Ex: the bones of the skull, as evident by
the suture lines at the joints
Bone elongation
o
Bones continue to grow until no more cartilage is left to replace
o
The site of bone elongation is near the ends of long bones;
epiphyseal plate
o
The epiphyseal plate is composed of 8 columns of cartilage cells
that divide, pushing the older cells towards the middle
o
The oldest cartilage cells get replaced by newer bone, thus the
bone is older the closer it is to the middle.
o
Long bones grow in length, circumference, and density
6
Joints
The place where two bones meet
 Fixed: permit no movement
o found in skull, connecting boney plates
 Semi-movable: permit limited movement
o Between the bones of the vertebral column, except the top two
(separated by disks of cartilaginous tissue that absorb shock)
o Connects the upper 10 pairs of the ribcage to the sternum,
allowing lungs to expand
 Movable: wide-range of movement
o Hinge [elbow, knees...]
o Ball-and-socket [shoulder, hips...]
o Pivot [cervical vertebrae]
o Saddle [base of thumb]
o Gliding [ found between the small
bones in the foot and inside the
wrists]
7
Joint structure and disease
The places where two bones meet is
covered with cartilage that protects
the bone surface from friction.
Ligaments: tough bands of connective
tissue that hold bones of a joint
together
Synovial fluid: secreted from
membranes in the joints that lubricates
(protects from friction) and nourishes
the tissues inside the joint.
Damage to the knee can cause swelling
in the compartments that contain
synovial fluid.
Disorders that cause painful, swollen
joints are described by the term
arthritis.
Arthritis
Rheumatoid
Autoimmune disease
Inflamed, swollen, stiff,
deformed joints
Genetic disease
Ligaments: Bone
Tendons: Muscle
Osteoarthritis
Degenerative
Thinner cartilage, bone on
bone rubbing sensed by
periosteum nerves
Age-related
Bone
Bone
8
Section 1.3: Muscular System
 The muscular system makes up 1/3 of
body weight (about 600 muscles)
Was
 Muscles enable the body to move, and
provide the force that pushes substances
throughout the body
 Muscle cells are called muscle fibers.
Bundles of these fibers are called
fascicles.
 Bones are only pulled by muscle
Types of muscle:
Skeletal
• Voluntary
• Multinucleated
 Moves parts of the
body such as the
limbs, trunk and
face
Cardiac
Single-nucleus 
 Striated
Involuntary 
 Found only in the
walls of the heart;
pumps blood
Smooth
 Non-striated
 Lines the walls of the
stomach, intestines,
and blood vessels
 Also found in the
uterus, digestive
tract, and bladder
 Responsible for
moving substances
throughout the body
9
Muscle structure
How are muscles organized?
In descending order of size:
Muscle (deltoid)  Fascicles  Muscle fiber  Myofibrils 
Sarcomere (z-lines in between)  Myosin & Actin filaments
 A large amount of nerves, blood vessels, and connective tissue
(covers and supports muscle fibers) also makes up a muscle
 Muscles rely on an active supply of oxygen and nutrients, which are
provided by arteries
 Muscles produces metabolic waste, which is carried away by veins.
 Muscle fibers contain bundles of threadlike structures call
myofibrils.
 Protein filaments make up the each myofibril. The thick ones are
myosin and the thin ones are actin. These filaments are arranged in
an overlapping pattern that gives striated muscles their striped
appearance
 Actin filaments are anchored at their endpoints to a structure called
z-line. The region from one Z-line to the next is a sarcomere.
10
Muscle contraction
 The basic functional unit of the muscle is the sarcomere.
 Muscle contraction begins at the nerve impulse that initiates it.
 The myosin heads attach to points between the beads of actin.
 The myosin heads bend inwards, let go of the actin, then bend
inwards again. Shortening the sarcomere.
 During contraction the overlap zone of the filaments increases.
 Synchronized shortening of many sarcomeres causes the entire
muscle to contract.
 Muscles require ATP to detach the myosin heads from the actin. A
continuous supply of ATP is required for proper muscle movement.
 Rigor mortis is a condition in which all muscles of the body become
rigid shortly after death because the body stops making ATP.
 Muscle contraction is an all or nothing response. The force of the
contraction is determined by the number of stimulated muscle
fibers.
11
Muscular Movement of Bones
 Muscles are attached to the periosteum either directly or
through a tough fibrous cord of connective tissue called
tendons
 The point where a muscle attaches to a stationary bone is
called an origin. The point where the muscle attaches to
moving bone is called an insertion
 Most muscles are arranged in opposing or antagonistic
pairs. Ex: Bicep/Triceps. When one contracts the other
relaxes, and vice versa.
 Flexors (biceps) bend joints. Extensors (triceps) straighten
joints.
 Both triceps and biceps have origins in the Scapula
 Bicep insertion is the Radius.
 Triceps insertion is the Ulna.
12
Muscle Fatigue
The physiological inability of a muscle to contract.
 Muscle energy use:
o Glucose  Glycogen (when glucose is unavailable)
 Fat (when stored glycogen runs out)  Fatigue
 Muscle fatigue is a result of a relative depletion of ATP.
 Absence of ATP cause continuous contraction
Oxygen debt
 𝟔𝑶𝟐 + 𝑪𝟔 𝑯𝟏𝟐 𝑶𝟔 ⇒ 𝟔𝑯𝟐 𝑶 + 𝟔𝑪𝑶𝟐 + 𝑨𝑻𝑷 (for knowledge)
 Oxygen is required for ATP synthesis through cellular
respiration.
 After heavy exertion, the cardiovascular and respiratory
systems can’t keep up with the oxygen demand for energy
production.
 Temporary lack of oxygen is called Oxygen debt.
 Lactic acid and metabolic waste buildup in the muscle fibers.
Causing soreness from the acid.
 CO2 is no longer produced in the muscle either.
13
Section 2.1: The Circulatory System
Circulation
Cardiovascular
Blood
Heart
Lymphatic
Blood
vessels
Lymph
Lymph
nodes
Lymph
vessels
 The circulatory system is the transport system of the body
 It transports nutrients, hormones, gases. Gets rid of waste.
Helps maintain constant body temperature (37 0 C)
The Heart
 The heart is a muscular
organ that pumps blood
throughout the body
 Located in the thoracic
cavity, behind the sternum,
between the two lungs.
 Surrounded by a tough,
saclike membrane called
the pericardium. Secretes
a fluid that reduces friction
 A septum (wall) divides
the heart into two sides,
and prevents blood from
mixing.
 Upper chambers are called
atrium. Lower are called
ventricle
 The atrioventricular valves (AV)
prevent blood from flowing back
into the atria
 The semi-lunar valves (SL)
prevent blood from flowing back
into the ventricles.
14
Circulation in the Heart
 There are 6 blood vessels
that enter the heart (2
vena cava & 4 pulmonary
veins)
 2 blood vessels exit the
heart (Aorta and
Pulmonary artery)
 The largest blood vessel is
the Aorta
 The thickest chamber is the
left ventricle
 Blood is dark red when
deoxygenated and bright
red when oxygenated.
 The pulmonary artery is the only artery carrying
deoxygenated blood
 Pulmonary veins are the only veins that carry oxygenated
blood
 Highest blood pressure is in aorta, lowest is in the vena
cava’s
15
Control of the Heartbeat
 A group of specialized cells control the
heartbeat (both the in the right atrium)
 The sinoatrial node spontaneously sends out
its own electrical signal every 0.8s (without
input from neurons)
 The sinoatrial node is called a pacemaker
because it regulates heart rate.
 The sinoatrial node causes the atria to contract
(0.1s) [auricular systole]
 The signal sent by the sinoatrial node is
received by the atrioventricular node
(located in the septum between two atria)
 The atrioventricular node causes the ventricles
to contract (0.3s) [ventricular systole]
 Ventricles an atria relax (0.4s) [diastole]
 A pulse is the series of pressure
waves caused by the contraction of
the left ventricle.
 An electrocardiogram (ECG)
measures pulse
 Closing of valves causes a lub-dub
sound
Auricular
systole
(0.1s)
Ventricular
systole
(0.3s)
• AV valves
open; SL valves
close
• Dub sound
• AV valves
close; SL valves
open
• Lub sound
Diastole
(0.4)
• Both valves
closed
16
Blood Vessels
The circulatory system is a closed system, the blood is either in the blood vessels
or in the heart at all times. Blood flows in one direction.
 Arteries are thick, muscular vessels that carry blood away
from the heart
 They need to be strong and elastic to prevent bursting from
blood pressure
 The structure of arteries from innermost to outer most:
o Endothelium  Smooth muscle  Connective tissue
 Blood pressure is highest in the Aorta and Pulmonary
arteries
 Two types of blood pressure
o Systolic: contraction of the ventricles (120 mm Hg
male 110 mm Hg female)
o Diastolic: disappearance of sound; steady flow ( 80
mm Hg male, 70 mm Hg female )
 Hypertension: high blood pressure, may cause vessel to
burst.
 Blooding coming out in random spurts out of a wound
means an artery was cut.
 Arteries divide into smaller blood vessels called arterioles
 Arterioles branch into a network of tiny vessels called
capillaries (whose walls are one cell thick)
 There is a capillary near every cell
 Substances diffuse through capillary walls following
concentration gradients.
 Capillaries merge into venules.
 Venules merge into veins.
 Veins merge to form the superior (upper) & inferior (lower)
vena cavas
 Veins are thin and less muscular than arteries with valves
inside because they undergo less pressure on their walls
than arteries.
17
Patterns of Circulation
 Discovered by William Harvey
 Pulmonary subsystem
Closed system
Circulation
Heart ↔ Lungs
 Systemic subsystem Heart ↔ other
body tissues.
Hepatic (liver)
portal
Systemic
Pulmonary
Renal
(kidneys)
Coronary
(supply to
heart)
Pulmonary Circulation
 Right ventricle 
Lungs  Left atrium
 Carries deoxygenated blood
 Pulmonary artery branches into two (one
for each lung)
 CO2 diffuses out, O2 diffuses in (at the
lungs)
 Venules merge into the pulmonary veins
Systemic Circulation
 Left ventricle  Body  Right atrium
 Heart and all parts of the body except
lungs
 Has other subsystems
 Coronary subsystem supplies blood to
heart itself
 Any type of cutting or blocking of
coronary arteries can cause heart attack
 Atherosclerosis is the buildup of fatty
material in the interior walls of coronary
arteries
18
Lymphatic System
A one-way path to the heart that returns protein-less,
Fluid that has collected in the tissues to the bloodstream
 Protein-less fluid that has diffused into
lymph capillaries (similar to blood
capillaries) is called Lymph.
 Lymph capillaries merge into lymph
vessels, which have similar structure to
veins (meaning they have valves)
 Lymph vessels return lymph to the heart
through the superior vena cava.
 Lymph nodes: small organs that filter
lymph from
o Foreign particles
o Microorganism
o Tissue debris
 Lymph nodes also contains lymphocytes
(W.B.C’s that are specialized to fight
disease)
 Nodes get inflamed, swollen, & tender
due to an increase in the no. of
lymphocytes after an infection
19
Section 2.2: Blood
The functions of blood are to transports nutrients and oxygen to cells, and
carry CO2 & other waste materials away. It also transfers heat to the body’s
surface & plays a role in disease defense
 Composition of blood (4-5 liters in normal body)
o 55% Plasma
o 45% R.B.C, W.B.C, & Platelets
 Plasma
o 90% water
o 10% nutrients, wastes, metabolites, proteins, & salts
o Contains [minerals, vitamins, amino acids & glucose]
absorbed from the digestive system that provide nourishment
to cells
o Carries hormones
o A variety of proteins
 Albumin
 Regulation of osmotic pressure.
 Fibrin
 Formation of blood clots.
 Antibodies
 Fight diseases.
20
Red Blood Cells
Erythrocytes
 Formed in red bone marrow
 Immature cells produce large amounts
of hemoglobin
o Hemoglobin is the ironcontaining protein that binds to
oxygen (and CO2)
 Mature cells lack a nucleus
 They have a life span of 120-130 days
White Blood Cells
Leukocytes
 Formed in red marrow but must travel to other
organs to mature
o [spleen, thymus, lymph nodes, tonsils]
 1mm3 blood 
o 4 mil R.B.C, 7k W.B.C, 500k Platelets
 Help destroy invading organisms and can live
for several years
 Phagocytes (neutrophils and macrophages)
o Engulf & ingest microorganism
 Plasma cells
o Produce antibodies
 Leukocyte count can double when person has
an infection
21
 Essential to the formation of blood clots
(preventing excess blood loss)
Platelets
Blood-clotting
Congregate at the damaged site
 Life-span of 7-12 days
 Made from fragments of very large cells
formed in the bone marrow
 Release a clotting factor: Fibrin
 The absence of one or more clotting factors
is Hemophilia
o Large cuts or internal injuries can be
life-threatening.
o Treated with protein injections
22
Blood Types
The A-B-O system of blood typing is based on the A & B
antigens on the surface of the R.B.C.
 Antigens are substances that stimulate immune response
o “anti-body generating substance”
o All pathogens are antigens but not all antigens are
pathogens
 Agglutination is when two samples of different blood type are
mixed together
o A reaction between antigens on the surface of the r.b.c.
and the antibodies in the plasma
o First observed by Karl Landsteiner
 It is necessary to know the antigens of the donor and the
antibodies of a recipient in a blood transfusion.
 AB blood is a universal recipient, O is a universal donor
 The Rh factor (named after rhesus monkey) is also another
antigen found on the r.b.c. (Rh-  no factor, Rh+  has factor)
 Erythroblastosis fetalis: Rh- mother and Rh+ father have a Rh+
child  mother develops antibodies against factor  second
child’s blood is attack by mother’s immune system
23
Section 2.3: The Respiratory
System
Internal respiration:
Exchange of gases between
blood and cells
External respiration:
Exchange between
atmosphere and blood
The Lungs
 The site of gas exchange between blood and atmosphere
 The left lung has 2 lobes and the right has 3 lobes (to make space for the
heart)
 Located in the Thoracic cavity bound by rib cage and diaphragm.
 A membrane called the pleura lines the cavity and secretes a fluid that
decreases friction
The Path of Air
 The nasal cavity filters air
 Pharynx has passage ways for both food and air
 The Trachea & Bronchi are lined with smooth muscles, cilia,
mucus, and cartilage
o The bronchioles have no cartilage (they have the rest)
 Alveoli are tiny air sacs surrounded by capillaries where all
exchange of gases occurs
o 300 million alveoli with a large surface are (70 m2)
o The surface area increases the rate of diffusion
24
Gas Exchange and Transport
 The driving force behind the diffusion of gasses between alveoli and
the bloodstream is the concentration gradient of CO 2 and O2
O2 molecules travel from the
area of high concentration
(alveolus) to lower
concentration (capillary)
CO2 molecules travel from
the area of high
concentration (capillaries)
to lower concentration
(alveoli)
Transport of Oxygen
 95-98% of oxygen moves in the r.b.c where it binds to hemoglobin
o
2-5% is dissolved in the plasma
 Each Hemoglobin molecule (Hb) contains 4 iron atoms
o
Each Iron atom can bind to one oxygen molecule
o Hb + 4O2 ⇌ HbO8  oxyhemaglobin
o The Hb molecule can carry up to 4 O2 molecules
 When oxygen reaches the cells:
o The reaction is reversed and oxyhemaglobin disassociates:
 HbO8 ⇌ Hb + 4O2
o Oxygen is used to break to break down glucose to make ATP by
the process of aerobic respiration
25
Transport of Carbon Dioxide
 70% of CO2 is transported as bicarbonate ions (HCO3-)
o 7% is dissolved in plasma
o 23% binds to hemoglobin
 Reaction at the cell:
+
o H2 O + CO2 ⇌ H2 CO3 ⇌ HCO−
3 +H
o High concentration of CO2 in the blood makes blood acidic
 Reaction at the lungs (reverse)
+
o HCO−
3 + H ⇌ H2 CO3 ⇌ H2 O + CO2
o The CO2 diffuses into the alveoli and is exhaled into the
atmosphere
Mechanism of Breathing
 Inspiration
o Lower air-pressure inside lungs; higher
outside. Air rushes in.
 Chest expands
 Diaphragm flattens
 Muscles contract to move ribs
move up and outward
 Abs relax
 Expiration
o
Higher air-pressure inside lungs; lower
outside. Air rushes out

Diaphragm and rib muscles relax

Abs contract

Chest shrinks
 The rate of breathing is controlled by
the brain and brainstem
o They monitor CO2 levels in the
blood
 A person can temporarily override the
control system and take manual
control
26
Section 3.1: Nonspecific Defenses
How the body identifies agents that cause infectious disease and
defends itself against them.
Koch’s Postulate
 Developed by Robert Koch
 First used to identify anthrax (bacteria)
 A step-by-step procedure to identify pathogens
Disease
Pathogen
Transmission
Common cold
Rhinovirus
N/A
Botulism
Contaminated food
AIDS
Clostridium botulinum
(bacterium)
Entamoeba histolytica
(protist)
HIV (virus)
Athlete’s foot
Tinea (fungus)
Amebic dysentery
Contaminated food
and water
Sexual contact,
contaminated
needles/fluids, mother
to fetus or infant
Contaminated surfaces,
person-to-person
contact.
27
First line of defense: Barriers
Mucous membranes
 Epithelial tissues that secrete mucous
o Sticky substance that traps pathogens
o Swept by beating cilia to the pharynx where it is swallowed
o Lines the organs of respiratory system, urethra, vagina, and
digestive system
 Protect the interior surfaces of the body.
Skin
 Physical barrier against pathogens
 Secretes sweat, oil, & waxes
o A special enzyme called lysosome in sweat destroys pathogens.
 This paragraph is
poorly printed in many
copies of the book
28
Second line of defense: Nonspecific immunity
Inflammatory response
 A series of events that suppress pathogens and speed up recovery
 Stimulated by invading pathogens
 Histamine is released
o Increases the permeability of blood capillaries
o Causes redness, warmth, swelling, pain
o Increases blood flow to damaged area
o Attracts phagocytes to the site of infection
 Phagocytes: ingest & destroy foreign matter
o Macrophages
 Large cells that engulf pathogens
 Some are stationary & others seek pathogens
o Neutrophils
 Most abundant type
 Circulate the bloodstream
 Natural killer cells
o Attack pathogen infected cells—not pathogens themselves.
o Effective at killing cancer cells and virus-infected cells
o Kills by piercing the membrane allowing water to rush in.
29
Temperature response
 Chemicals secreted by macrophages and certain pathogens cause
fever
 A temperature above 370 C is considered a fever
 A high temperature (390 C) causes a break down in the proteins of
cells (denaturation). >410 C is fatal.
Proteins
 About 20 proteins make up the complement system that circulate
the blood and become active when encountering pathogens.
 They can form ring-shaped structures and puncture the
membranes of infected cells
 Interferon
o Protein released by virus-infected cells; helps nearby cells to
resist viral infection.
o Some experiments show it has an ability to cure some types
of cancer
30
Section 3.2: Specific Defenses
The Immune System
Leukocytes
Organs
Lymphocytes
Adenoids
Phagocytes
Neutrophils
Natural
killer cells
B cells (made
in marrow)
T cells (made
in marrow)
Thymus
(above heart)
Site of maturation
Macrophages
Spleen
Site of maturation
*B cells can also mature in
marrow
Tonsils
Lymph nodes
Bone marrow
31
Recognizing pathogens
 Lymphocytes provide specific defense because they can recognize
antigens
o Any foreign bodies that the body doesn’t recognize
o Pathogens & their parts, pollen, toxins, venom, foreign molecules
 Lymphocytes bind to antigens to start the immune response.
 There are millions of lymphocytes with different receptors on their
surface
 The different receptors can bind to different antigens
 The lymphocytes react to the binding
 Specific comes from the specificity of the antigens and the
complementary receptor shapes they can bind to
32
Immune response
Cell mediated
Humoral
 Both immune responses occur at the same time and require a specialized
cell called helper T-cell.
 The first step in both responses is a macrophage engulfing a pathogen and
displaying its antigens on the surface membrane
o Macrophages release the cytokine (protein) interleukin-I when a
helper T-cell binds to the antigens displayed.
 The release of IL-1 activates more helper T-cells, which release
interleukin-II
 IL-2 stimulates production of cytotoxic T-cells & and further division of
helper T-cells
 Cell-mediated
o Actions of the T-cells
o IL-2 stimulates production of cytotoxic T-cells & and further
division of helper T-cells
 Cytotoxic T-cells attack cells infected by pathogens & some
cancers by making a hole in the membrane of the cell
 CT T-cells also attack parasites and foreign tissues
o Suppressor T-cells play a role in shutting down the immune
system after the pathogen has been cleared from the body
 Humoral
o Actions of the B-cells
o IL-2 stimulates B-cells that have complementary antigens to
divide and change into plasma cells (some become memory cells)
 Plasma cells make defensive Y-shaped proteins called
antibodies that bind to a specific antigen on the pathogen
surface (30,000 antibodies per second)
 Antibodies do not destroy directly; but either deactivate or
cause destruction by nonspecific defense (like clumping
pathogens together for macrophage food or activating the
complement proteins)
33
Cell-mediated response
Humoral response
34
Primary and Secondary Immune Response
 The first time a person is infected by an antigen is called a primary
immune response
o Memory cells are created during the primary response (they do not
respond for the first time)
 Memory cells can quickly recognize and attack during later infection;
called the secondary immune response
o The second responds is faster and more powerful
 Cold and flu are an exception because the viruses that cause them mutate
at a high rate and are always presenting new antigens
Immunity & Vaccination
 Immunity: The ability to resist infectious disease. It can be achieved by:
o Being infected and undergoing the primary immune response
o Vaccination
 Introduction of antigens to the body to cause immunity
 A vaccine contains a solution of dead or weakened
pathogens
 Diseases controlled by vaccination {polio, measles, mumps,
tetanus, diphtheria, smallpox}
 Sometimes booster shots are required to restore immunity
(tetanus & polio)
35
Problems of the Immune System
 Allergies
o A physical response to an antigen {pollen, dander, dust mites, food,
fungal spores, }
o Symptoms of allergies are generally mild {sneezing, runny nose,
watery eyes, itchy swelling of skin}, but some can be lethal
o Much of the symptoms of allergies are cause by Histamine release
 Can be treated with antihistamines
 Asthma (symptom of allergy)
o Narrowing of the bronchioles due to substances in the air, making
breathing difficult
o Other respiratory tissues may also swell and become inflamed.
 Autoimmune disease: Immune system attacks body
o Lymphocytes that react to antigens in the body are quickly
destroyed but sometimes they survive
Disease
Tissues affected
Symptoms
Lupus
Connective tissue
Type I Diabetes
islets of Langerhans
Rheumatoid arthritis
Psoriasis
Multiple sclerosis
Joints
Skin
Nervous tissue
(insulating material)
Facial rash, joint pain, fever,
fatigue, kidney problems,
weight-loss
Excessive urine production
and thirst, weight-loss, fatigue,
confusion
Inflammation of joints
Dry, scaly, red skin-patches
N/A
36
Section 3.3: HIV & AIDS
 HIV is the virus; AIDS is the disease (acquired immunodeficiency
syndrome)
 The virus is transmitted through
o
Sexual contact
o
Contaminated syringes or hypodermic needles
o
Mother to fetus/infant (breast-feeding)
 The virus is NOT transmitted through
o
Casual contact (Hand-shakes)
o
Air, water, toilet seats
o
Insect bites
 HIV binds to the CD4 receptor & CCR5 co-receptor on macrophages
o
The virus replicates inside the macrophage (budding)
o
HIV mutates inside the macrophage and is released without the
phagocyte dying.
o
Mutations allow the virus to recognize receptors on other cells like
helper T-cells

T-cells do not have co-receptor CCR5
 After binding to the helper T-cell, the virus replicates. This destroys the
T-cells.
 The decreased no. of helper T-cells cripples the immune system, this
effect progresses to AIDS when the helper T-cell count falls below 200
cells per 1 ml blood.
37
Phases of Infection
 Phase I
o Asymptomatic stage, can last up to 10 years
o Immune system attacks virus, viral replication occurs
o Anti-HIV antibodies after several weeks are produced so an HIV
test can be performed.
o Possibility of infecting other people even if there no symptoms.
 Phase II
o Beginning or worsening of symptoms
o B cells (Plasma cells) continue to produce antibodies (Antibody
test can performed in this phase)
o Swollen lymph glands, weight-loss, diarrhea, forgetfulness, fatigue,
fever, abnormal thinking patterns.
 Phase III
o Helper T-cell count falls drastically. HIV count increases

T-cells can no longer stimulate B cells or cytotoxic T-cells to
fight off the virus
o AIDS is diagnosed when T-cell count falls below 200 cells/ml
blood (normal is 600-700) or opportunistic infections develop:

Otherwise harmless diseases that are made worse by the
crippled immune system

Pneumocystis pneumonia, tuberculosis
o HIV itself does not cause death, but the inability to fight off
infection is lethal.
 There is no vaccine because the virus frequently mutates & becomes
quickly resistant to drugs. 3 different types of drugs, 50 pills a day is the
standard treatment. Avoid high-risk behavior.
38
Section 4.1: Neurons & Nerve Impulses
The nervous system is responsible for:
 Mental activities
 Physical activities
 Maintaining homeostasis
The functions of the nervous systems are carried out through nervous tissues which is
made up of nerve cells called neurons.
Neuron structure
 The cell body contains a nucleus most of the organelles
 Dendrites are membrane-covered extensions from the cell body that receive
signals from other cells.
 The axon is a long membrane-bound projection that carries the electrical signal
to a muscle, gland, or other neuron. The signal is called action potential
 Myelin sheaths (Produced by Schwann cells in non-CNS neurons) are lipid
bilayers that insulate the axons, speeding up the transmission of action
potential
o The gaps in between sheaths are called nodes of Ranvier.
 The axon terminals are at the end of a neuron and terminate in the synaptic
cleft, which joins the presynaptic neuron and the post synaptic cell.
 Neurons do not touch and communicate at the synapse.
 Neurotransmitters are sometimes released into the cleft to initiate action
potential in the postsynaptic cell (if enough potential difference is created)
 Thus, communication between neurons involves chemical flow and electrical
activity.
39
Nerve impulses
 All cells have a certain difference in charge across their cellular
membrane called membrane potential (measured in volts) produced by
ion movement across the membrane
 Membrane potential depends on:
o Ability of ions to diffuse across the membrane
o The concentration of ions inside and outside the cell (concentration
gradient)
o The charge of the ions
 Ions pass through proteins on the membrane called ion channels. Which
only allow certain ions under certain conditions
o For example, voltage-gated channels only open at certain
membrane potentials. Even a small change in voltage can affect the
permeability of the membrane.
Resting potential
 A neuron is at rest when it is not sending or receiving a signal
(Polarization)
 The inside of the neuron is more negatively charged than the outside due
to large negative-charge proteins that are unable to diffuse out of the cell
 The outside is positively charged mainly because of Na+ ions and some
K+ ions. Na+ cannot move freely into the cell, but K+ ions readily diffuse
through K+ channels down their concentration gradient.
 The resting potential is -70 millivolts
40
Action potential
 The stimulation of a dendrite or cell body changes the permeability of the
membrane, allowing a small no. of Na+ ions to flow into the cell interior.
Reversal of polarity begins action potential.
 If enough Na+ ions diffuse to create a certain threshold potential, the
voltage-gated Na+ channels open, causing a large no. of Na+ ions to flow
in (Depolarization)
 The interior becomes more positively charged than the exterior
 The action potential travels from where the cell body meets the axon, in
one direction, towards the axon terminals
 Voltage-gated channels exist along the length of the axon and open when
the travelling action potential reaches them
 Positive charge travels across the axon
 Na+ voltage-gated channels close shortly after they open, K+ channels
open; outward flow of K+ ions. The Na+ ions are pumped out by sodiumpotassium pumps and K+ is moved in. This action requires ATP.
(Repolarization)
 The neuron cannot generate another action potential until resting potential
(-70mv) is restored (Refractory period).
41
Neuron communication
 When the action-potential reaches the synapse, the vesicles fused with the
presynaptic membrane, releasing neurotransmitters into the synaptic
cleft
 Neurotransmitters diffuse across the cleft to bind to receptor proteins in
the postsynaptic cell and stimulate chemically-gated channels to allow
Na+ ion flow; continuing the electrical signal.
o Too few channels may open
 Not enough voltage for action potential in postsynaptic
membrane
o Other channels may open allowing negative proteins
 Potential difference becomes more negative; no action
potential in postsynaptic membrane
 Neurotransmitters are quickly reabsorbed or broken down by enzymes so
that their effect doesn’t last long.
42
Section 4.2: Structure of the Nervous System
Central (CNS)
Brain
Cerebrum
Diencephalon
2 Frontal
lobes
Thalamus
2 Parietal
lobes
Hypothalamus
Peripheral (PNS)
Spinal Chord
Brain Stem
2 Temporal
lobes
Sensory
division
Cerebellum
Motor
division
Somatic
Autonomic
Midbrain
Pons
Sympathetic
Parasympathetic
Medulla
oblongata
2 Occipital
lobes
 The brain in numbers
o 1.4 kg mass (2% of body weight)
o 100 billion neurons (10-20% are in the cerebral cortex)
 There are more neurons in white matter than the cortex
o The CNS interacts with the PNS through 12 pairs (24 total) of
cranial nerves that connect the brain with the head and neck, and
31 pairs (62 total) of spinal nerves that connect to the rest of the
body.
 43 pairs for interaction between CNS and PNS
 Neurons that carry signals away from the CNS are called efferent
neurons
 Neurons that carry signals towards the CNS are called afferent neurons.
 Both afferent and efferent neurons are part of the PNS.
43
Cerebrum
 The largest portion of the brain identified by its highly folded outer layer
called the cerebral cortex
o The cortex is made up of gray matter
 Made up of two hemispheres that are connected by a band of axons called
the corpus callosum
 The interior below the cortex of myelinated axons called white matter
that links regions together
 Functions in the brain are not symmetrically localized
o For example, the right-side controls reasoning and spatial
information while the left controls speech and language
 Due to crossover of neurons, many impulses originating in the right side
of the brain controls the left side of the body.
Diencephalon
 Above the brainstem and below the cerebrum, contains relay centers
 Thalamus
o Serves as a relay center and redirects sensory information to where
they are supposed to be interpreted inside the cerebral cortex
 Hypothalamus
o Maintains homeostasis
o Directly or indirectly controls the body’s hormone production
44
Brainstem
 Midbrain
o Relays visual and auditory information
 Pons
o A relay for communication between the hemispheres and the
cerebellum
 Medulla oblongata
o Serves as the as a relay center and a control center for:
 Respiratory rate
 Heart rate
 Other homeostatic activities
The Spinal Cord
 Column of nervous tissue that starts at the medulla
oblongata
 Inner core of gray matter (unmyelinated axons,
dendrites, and cell bodies) with a white matter
outer sheath
 Carries nerve signals back and forth.
Peripheral Nervous System
The peripheral nervous system interacts with the 12 pairs of cranial nerves and 31 pairs of
spinal nerves and interneurons that carries carry information between other neurons
Ventral roots

The ventral root is the efferent motor root and carries motor
information from the brain
Dorsal roots

The dorsal root is the afferent sensory root and carries sensory
information from sensory receptors to the brain
o Light, pressure, heat
o Sensory input travels in an orderly way (sensory input from
shoulders enters the dorsal roots of the upper spinal cord)
45
Sensory division
 Sensory receptors and the interneurons that connect them to the CNS
 Carry information from the body’s internal and external environments to
the brain
 Spinal and cranial nerves send sensory information
Motor division
 Made up of two independent systems—somatic and autonomic.
Somatic Nervous System
 Voluntary control of skeletal muscles
 Involuntary to maintain balance or spinal
reflexes that bypass the brain
o Sensory receptor  Interneuron
 Motor neuron
Autonomic Nervous System
 Controls internal body
conditions
 Regulates smooth muscle in
blood vessel
 Controls:
o Respiration
o Heart-rate
o Digestion
o Other aspects of
homeostasis
 Further subdivides into the
sympathetic (stimulation) and
parasympathetic (inhibition)
systems
46
Section 4.3: Sensory Systems
Certain sensory receptors respond to stimuli that turns into action
potential, and is carried to the CNS through afferent neurons to be
interpreted by regions in the brain
Categories of receptors
Mechanoreceptor
{Hair cells (ear), located throughout
Pressure, tension, movement
skin, base of hair follicles. Touch
receptors concentrated in face, tongue,
and fingertips}
Thermoreceptor
{cold receptors (<200) and heat
Changes in temperature
receptors in skin (300-450)}
Chemoreceptor
{taste buds, olfactory receptors}
Chemicals
Photoreceptor
{rods and cones}
Variations in light
Pain-receptor
{base of the epidermis, throughout
interior of body, high concentration in
Detect tissue damage. Stimulated
by mechanical, electrical,
chemical, and thermal energy
hands and mouth}
*The brain has a special region for each sense and any trauma or signal
received by that region is interpreted as a sensory input
o For example, a blow to the occipital lobe causes you to see “white
stars” because that’s the region involved in processing visual
information
47
Hearing & Balance
 The ear has two functions: hearing and balance
Auditory canal
Tympanic membrane
Ossicles (hammer, anvil, stirrup)
Oval window
Eustachian tube
Connects external ear to tympanic
membrane
The eardrum: vibrations in the air cause
it to vibrate as well
Transfer vibrations of the eardrum to
the oval window
Separates the middle ear and the inner
ear
Regulates air pressure in the middle
ear; equalizes the pressure on both
sides of the tympanic membrane.
Connects to the throat
Cochlea
 Located in the inner air
 Consists of 3 fluid-filled chambers
 Contains the organ of Corti (organ of hearing)
o Located in the middle chamber, bottom membrane
 Hair cells in the organ of corti bend against the 2nd membrane
o This opens ion channels, changing electrical potential releasing
neurotransmitters that stimulate the neurons in the auditory nerve
o Hair cells can be easily damaged by high frequencies
o A. potential  Auditory nerve  Midbrain  Thalamus 
Auditory cortex (temporal lobe)
Balance
 The semicircular canals are responsible for balance inside the ear
 Consist of three canals filled with fluid that contain hair cells
 The hairs have particles of CaCO3 on top of them
 When the head moves, the hairs move due to gravity or inertia of the calcium
carbonate
 The brain interprets the bending as motion and orientation in space
48
Oval window
Eustachian tube
Vision
Cornea
Pupil
Iris
Lens
Retina
Rods
Cones
A clear protective layer where light
passes through first
Controls the amount of light entering the
eyes
The colored part of the eye (contains
muscles)
A crystalline structure that bends light
rays
Light-sensitive inner layer
Contain rhodopsin and respond to dim
light
Stimulated by bright light; 3 kinds of
cones that respond to different colors.
Faulty or missing cones can cause
colorblindness
A. potential from optic nerve  Thalamus  Occipital lobe cortex
49
Taste and Smell
Taste
Taste buds
(10,000)
(embedded
between bumps
called papillae)
Partietal lobe
cortex
Chemicals
dissolved by
saliva bind to
receptors
Thalamus
Brain stem
Neurons on the
inner surface of
taste buds are
stimulated
Action
potential
Smell
Olfactory
chemoreceptors
located in the
mucous lining of
the epithelial tissue
of nasal passages
Amygdala
(limbic)
Odor binds to
receptor,
stimulating it
Action potetial
Olfactory
areas of the
frontal lobe
cortex
Olfactory bulb
(limbic)
50
Section 4.4: Drugs & the Nervous System
Drugs are substances that change a person’s physical or psychological
state. A psychoactive drug alters the functioning of the central nervous
system.
Addiction and Tolerance
 Abuse of psychoactive drugs leads to dependence
o Reliance on a drug physically or emotionally in order to
function
 Dependence leads to addiction
o Loss of control over drug use
 Addiction leads to tolerance
o Increase in effective dose to achieve the desired effect,
approaching a lethal dose that will kill a user
 Without the drug, addicts go through withdrawal
o Physical and emotional response to the drug’s absence
o Vomiting, headaches, breathing difficulties, depression, mental
instability, insomnia, seizures
 Cocaine (Erythroxylon coca) is a highly addictive stimulant drug
51
Alcohol
 A depressant that decreases the activity of the central nervous system
 Increases circulation to the skin, lowers body temperature, decreases blood
flow to internal organs. Respiration rate initially increases then slows down.
o High doses can cause death by respiratory failure.
 BAC is blood alcohol concentration
o There is an inverse relation between BAC and body temperature
o 0.30 or greater results in unconsciousness
o 0.50 or greater can be fatal
 Alcohol consumed during pregnancy can lead to fetal alcohol syndrome
(FAS)
Tobacco
 Highly addictive stimulant
 Mimic the neurotransmitter acetylcholine
 Increases blood pressure and heart rate, decreases oxygen supply to body
tissues and blood supply to hands and feet.
o 60mg is the lethal dose
 Tars are also produced when burning tobacco. Complex mixtures of
chemicals and smoke particles
o Coat and paralyze cilia
o Irritate nose, bronchioles, trachea, throat
o Disrupt lung cells
Diseases
Chronic bronchitis
Emphysema
Lip, gum, and mouth cancer
Inflammation of bronchi and
bronchioles
A degenerative disorder in which
alveoli lose their elasticity &
eventually rupture
Chewing tobacco and snuff
52
Section 5.1: Hormones
Slow acting chemical messengers with long lasting effects that
are part of the endocrine systems & send instructions to cells
Functions and Secretion
Endocrine hormones
 Regulate behavior
 Growth and development
 Regulate reproduction
 Respond to external stimuli
 Metabolism
 Water and mineral balance
Hormones and specialized cells are collectively called the endocrine
system
Endocrine glands
 Ductless glands that make and secrete hormones into the blood stream or
into extracellular fluid
 Hormones travel to target cells and bind to specific receptor proteins on
the cell membrane, in the cytoplasm, or in the nucleus
Exocrine glands
 Glands with ducts or tube-like structures that secrete substances inside
and outside the cell
o Sweat
o Mucous
o Saliva
o Water
o Enzymes
o Digestive glands
*Neurotransmitters are similar to hormones but they are part of the nervous system, have
shorter effects and don’t remain in the bloodstream for a long time.
53
Types of Hormones
Steroid (lipid or fat)
Amino-acid based (peptide)
Fat soluble, made from cholesterol
Single amino-acid or a protein made
up of 3-200 amino-acids
Can diffuse across the membrane,
binding to receptors in the cytoplasm
or nucleus
First messengers, have to bind to a
receptor protein on the membrane
Hormone-receptor complex activates
(or initiates the synthesis of ) enzymes
or proteins
Result in hormone-receptor complex
that activates an enzyme that turns
ATP to cAMP
Hormone-receptor complex binds to
DNA activating transcription of
mRNA
cAMP acts as a second messenger
that initiates a change inside the cell
Thyroid hormones are amino-acid
based but can diffuse through the
membrane
Can have other second messengers
Amino-acid based
Steroid or Thyroid
54
Other Types of Hormones
Neuropeptides (amino acid based)
Secreted by nerves cells and can affect many cells (unlike neurotransmitters
which only affect postsynaptic cells)
 Endorphins
o Regulate emotion, influence pain, and affect reproduction
 Enkephalins
o Inhibit pain messages travelling towards the brain.
Prostaglandins (modified fatty acids)
Secreted by most cells and accumulates in areas where tissue is damaged or
injured.
 Some raise blood pressure and others reduce it
 Some cause smooth muscles to contract and others cause them to
relax
 Some cause fever
o Aspirin and acetaminophen reduce fever and pain by reducing
prostaglandin synthesis
55
Section 5.2: Endocrine Glands
Hypothalamus & Pituitary glands
 Area of the brain that coordinates most hormone production, located in
the diencephalon.
 Responds to other brain regions and blood concentrations of circulating
hormones
 The pituitary gland is suspended from the hypothalamus by a short stalk.
 Anterior is regulated by blood vessels, posterior by axons
 Directly secretes oxytocin and antidiuretic-hormone (ADH) through
neurosecretory cells whose axon terminals extend into the posterior
pituitary gland, where they are stored
 Indirectly controls hormone production by secreting releasing and
release-inhibiting hormones through blood vessels that connect to the
anterior pituitary gland
o RH hormones stimulate the production of anterior pituitary
hormones
o RIH hormones inhibit the production of anterior pituitary
hormones
 Prolactin and growth hormone (GH) are regulated by both RH
hormones and RIH hormones
o Follicle stimulating hormone (FSH), Thyroid stimulating
hormone (TSH), and adrenocorticotropic hormone (ACTH) are
regulated by RH hormones
56
Thyroid gland
 Located under the larynx and on the trachea
 Two lobes
 Regulated by TSH (Thyroid-stimulating hormone)
 Produces and secretes:
o Thyroxin
o Triiodothyronine
Synthesized from the
same amino-acid and
iodine atoms
o Calcitonin
 Stimulates calcium ion reabsorption by bones, thus
decreasing Ca+2 levels in blood.
 Functions include
o Maintain normal heart rate, blood pressure, and body temperature
o Stimulate glucose-oxidizing, oxygen consuming enzymes.
o Generate heat and increase cellular metabolic rates
o Promote carbohydrate over fat usage for energy
57
Adrenal Glands
 The human body has two adrenal glands superior
to each kidney.
 Inner layer (adrenal medulla). Outer layer
(adrenal cortex)
o Secretion of hormones by the medulla is
directly controlled by the nervous
system
o Secretion of hormones by the cortex is
controlled by hormones from the anterior
pituitary
 Adrenal Medulla
o Secretion of amino acid based hormones epinephrine (adrenaline)
and norepinephrine (noradrenaline)
o Reaction to stress; fight-or-flight
o Increase heart-rate, blood pressure, blood glucose level,
enlargement of bronchial tubes, blood flow to heart and lungs,
dilation of pupils
 Adrenal Cortex
o Responds to ACTH released by anterior pituitary
 ACTH-RH is secreted by the hypothalamus (caused by
stress)
o Secretion of steroid hormones Cortisol and Aldosterone
 Cortisol promotes the production of glucose from proteins
 Aldosterone raises blood pressure and volume by
stimulating salt and water retention by the kidneys
 Note: ADH is different from aldosterone because it
stimulates reabsorption rather than retention.
58
Gonads: gamete-producing organs that also produce a group of steroid
hormones
Male
Female
 Testes
 Ovaries
 A group of sex hormones called
androgens
 LH + FSH stimulate the
production of Estrogen and
Progesterone
o Regulates secondary male
characteristic
o LH stimulates testes to
produce testosterone
 Testosterone + FSH stimulate
sperm production
 These hormones cause the monthly
release of an egg by an ovary
 Estrogen regulates secondary
female characteristics
Pancreas
 Mostly contains exocrine glands (that secrete digestive juices)
 The parts of the pancreas that function as endocrine glands are the islets
of Langerhans
 The islets produce two amino acid based hormones that regulate bloodsugar levels (BSL)
o Insulin simulates body cells (especially muscles) to store glucose
or use it for energy; lowering the blood sugar level
o Glucagon stimulates the release of glucose into the bloodstream by
liver cells
o Insulin and glucagon are antagonistic hormones (opposite)
 Insulin deficiency causes diabetes mellitus
o Excess glucose inhibits water reabsorption, large amounts of urine.
Acid-base/electrolyte imbalances. Nausea, rapid breathing, heartirregularities, depression, coma, death.
o Type I is autoimmune
o Type II results from insufficient insulin or unresponsive target
receptors
 Excessive insulin causes hypoglycemia
59
Thymus
 Beneath the sternum, between the lungs and above the heart
 Produces the hormone thymosin (amino-acid based )
o Stimulates the maturation of T cells
Pineal gland
 Located near the base of the brain
 Secretes Melatonin
o Melatonin concentration is low during the
day and high during the night, which
suggests that it has role in regulating sleep
patterns.
Parathyroid
 4 glands embedded in the lobes on the thyroid (2 in each lobe)
 Secrete the parathyroid hormone
o Stimulates the transfer of calcium ions from bone to the
bloodstream
o Antagonistic to calcitonin
o Proper calcium balance is important for
cell-division, muscle contraction, blood
clotting, neural signaling
Digestive cells
 In the walls of digestive organs; regulate digestive processes
 Cells in the stomach lining secrete gastrin
o Stimulates production of digestive enzymes and HCl
 Cells in the small intestine lining secrete secretin
o Stimulates the release of digestive fluids from the pancreas
60
Problems with endocrine glands
Disease
Related gland or
organ
Cause
Symptoms &
treatment
Hyperthyroidism
Thyroid
Overproduction of
thyroid hormones
Hypothyroidism
Thyroid
Thyroid-hormone
deficiency
Cretinism
Thyroid
Hypothyroidism
Over activity,
weight –loss, high
blood pressure,
heart rate, and
body temperature.
Treated with
medication or
surgery
Growth
retardation,
lethargy, weight
gain, low heart rate
and body temp.
Treated with
thyroxine
supplements
Mental retardation
Goiters
Thyroid
Iodine-deficiency
Diabetes type I
Pancreas
Immune system
attack islets of
Langerhans
Diabetes type II (more
common that type I)
Pancreas
Hypoglycemia
Pancreas
Heredity, but also
correlates with
obesity and
unhealthy lifestyle
Excessive insulin;
glucose is stored
rather than being
properly delivered
Same as
hypothyroidism
but different cause
Treated with daily
injections of
insulin and
sometimes islet
transplants
Controlled through
exercise and diet.
Lower BSL causes
release of glucagon
and epinephrine.
Lethargy,
dizziness,
nervousness, over
activity,
unconsciousness,
even death
61
Feedback Mechanisms
 To maintain homeostasis, feedback mechanisms control hormone
secretion
 A feedback mechanism is one in which the last step in series controls the
first
Negative Feedback
 The final step in the series inhibits the first
 Thyroid hormones & Testosterone are an
example of hormones regulated by negative
feedback
 An increase in thyroid hormone concentration
inhibits the release of TRH in one loop and
TSH in another loop
o This causes a decrease in the
concentration of thyroid hormones and
thus a decline in the negative feedback inhibition
Positive Feedback
 The final step in the series stimulates the first, causing further release
of the secondary substance
 Increased Estrogen stimulates the production of LH prior to
ovulation. LH stimulates further production of estrogen
62
Section 6.1: Male Reproductive System
 The role of the male in reproduction is to
produce an deliver haploid (1n) sperm cells to
fertilize and egg cell
 Testes are egg-shaped organs that are the site
of androgen and sperm production
o 2.5 cm in diameter and 4 cm long
o Made up of 250 compartments
o Formed in the abdominal cavity and
descended into a sac-like structure
(scrotum) before birth
 The scrotum interior is 2-30C
cooler than the internal body temp.
(370)  (34-350 in scrotum)
 Slightly cooler temperatures are necessary for sperm
development
 Seminiferous tubules are tightly coiled tubules contained in the
compartments of testes, each 80 cm long
o Sperm are produced in the lining of the tubules through meiosis but
mature in the epididymis
Sperm formation
 LH stimulates the cells between seminiferous
tubules to secrete testosterone
 FSH + Testosterone stimulate sperm production
in tubules
o 4 immature haploid sperm are formed
from each cell undergoing meiosis
 Mature sperm has a head that contains the nucleus
(23 chromosomes) and digestive enzymes
 Midpiece contains mitochondria that supply
energy
 Tail (flagellum) that propels the sperm
63
Path of Sperm
Seminiferous tubules (testes)  Epididymis (2)  Vas deferens (2)
 Urethra (where sperm mixes with fluid from 3 other glands)
 The epididymis is a long, coiled tubule closely attached to each testes and
is the site of maturation of sperm
o Immature sperm consists of a head and midpiece. Flagellum fully
develops inside the epididymis
 Vas deferens is a duct with smooth muscles that help move sperm.
o Each vas deferens loops around the bladder and merges with the
urethra
 The Exocrine glands
o Seminal vesicles
 In between the bladder and rectum
 Secrete a sugar-rich fluid that provides energy for the sperm
o Prostate
 Below the bladder
 Secretes an alkaline fluid that neutralizes acidity in the
female reproductive system
o Bulbourethral glands
 Secretes an alkaline fluid that neutralizes the acidity of trace
urine in the urethra
 Semen
o
Forcefully expelled by contractions of the smooth muscle in
urethra (ejaculation)
o
Most sperm are killed by the acidic environment of the female
reproductive tract
o Composition
 Seminal vesicle fluid + Prostate fluid + Bulbourethral
fluid + Sperm (10% of volume, 300-400 mil sperm) +
Prostaglandins (stimulate smooth muscle contractions in
female reproductive system)
64
Path of sperm in the male body
Section 6.2: Female
Reproductive
System
 Ovaries are two almondshaped, gamete-producing
organs located in the
abdominal cavity of the female
body
o 3.5 long and 2 cm diameter
 Fallopian tubes or uterine tubes are lined with cilia and smooth muscles
that move mature eggs from ovaries to the uterus
 The uterus is a hollow, muscular organ where a fertilized egg develops
 The cervix is the lower entrance to the uterus in which there is a sphincter
muscle that controls the opening
 The vagina is a muscular tube that leads outside of the body from the
cervix
o Receives sperm from the penis
o Channel through which a baby passes during childbirth
65
Formation of Eggs
 A female is born with 400,000 immature eggs of which only 300-400 are
released (<1%) during a lifetime. One every 28 days via the ovarian
cycle
 Eggs form through meiosis. Unlike sperm, each cell that goes through
meiosis produces 1 functional egg
 Immature eggs are stalled in prophase I. Meiosis I (D) continues during
puberty when sex hormones stimulate egg
maturation
o 10-20 eggs resume meiosis, but
generally only one (C) completes it
o One of the haploid cells (E)
receives most of the cytoplasm, can
become a mature egg
o The other haploid cell (F) is called
the first polar body and dies
 Meiosis II (G) is not completed until
ovulation occurs and a sperm fertilizes the
egg
o If fertilized, the egg completes the
final meiotic division into the
mature egg or ovum (H)
 The ovum receives most of
the cytoplasm, which provides nutrients for the egg. It is
75,000 times larger than a sperm
o The other haploid cell (I) is called the second polar body and dies
66
Preparation for Pregnancy
 The ovarian/menstrual cycles are simultaneous and repeat every 28 days
 Hormones secreted by the ovaries and anterior pituitary glands regulate
the ovarian cycle
 Follicular phase
o
Lasts 14 days of the ovarian cycle
o
The hypothalamus secretes a releasing hormones that stimulates the
release of FSH from the anterior pituitary
o
FSH stimulates mitotic divisions of follicles in the ovaries that
nurture an egg (provide nutrients)
o
The follicles begin secreting estrogen, which stimulates mitotic
divisions in the uterus making the lining (endometrium) thicker
o
Meiosis I is complete in this phase
o
The increase in estrogen concentration is a positive feedback
mechanism that causes an increase in LH levels which marks the
end of the follicular phase
 Ovulation phase
o
A sharp rise in LH midway in the cycle causes the follicle to
rupture and release the egg; ovulation
o
The egg travels to the surface of the ovaries and is swept into a
fallopian tube. It has enough nutrients to survive for 24 hours
 Luteal phase
o
o
Lasts another 14 days
o
The corpus luteum begins secreting estrogen and progesterone
The follicle cells grow larger to fill the cavity left from the release
of the egg, forming a new structure called the corpus luteum
(yellow body)

o
Progesterone stimulates the growth of blood vessels and
storage of fluids and nutrients in the lining of the uterus
The increase in progesterone + estrogen act as a negative
feedback mechanism on LH & FSH
67
Menstruation
 If the egg is fertilized it becomes a zygote and is implanted in the uterus
where it will gestate for 9 months
 If the egg is not fertilized the concentrations of estrogen and progesterone
will drop and the thickened uterine lining will rupture and slough off
to be discharged through the vagina
o
This is known as menstruation and it lasts for 5-7 days of the
follicular phase
 Women will continue to menstruate until about age 50 when there are not
enough follicles and the ovarian/menstrual cycle will stop; this is called
menopause
68
Section 6.3: Gestation
Fertilization
 Path of sperm to egg
o Vagina  cervix  uterus  fallopian tubes  egg
 Can occur 72 hours before, or 48 hours after, ejaculation
 The egg released from the ovary is encased in a jelly-like substance
and cells from the follicle
 Multiple sperm can attach to the membrane of the egg but only one
fertilizes it
 Digestive enzymes in the head of the sperm allow it to penetrate
the membrane of the egg
 When one sperm passes through the egg membrane and fertilizes
it, electrical charges released from the egg membrane keep the
other sperm attached to the egg away
o Only the head and midpiece of sperm enter the cell, the tail
(flagellum) remains outside
 The fertilized egg completes Meiosis II
 When the nuclei of the egg and sperm combine, the cell becomes
the 2n, 46 chromosome zygote. This begins gestation
Cleavage and Implantation
 The zygote then begins a series of mitotic divisions called cleavage
o This results in a ball of cells no bigger than the zygote
called morula
 The morula then divides again resulting in a structure called a
blastocyst: A ball of cells with a large, fluid-filled cavity
o The blastocyst secretes an enzyme that breaks down the
epithelial tissue of the uterus. This allows it to burrow and
embed itself in the endometrium or uterine lining in a
process called Implantation
 Implantation occurs 1 week after fertilization and
begins pregnancy
69
Fertilization, cleavage & implantation
Pregnancy
Pregnancy is divided into three equal periods or trimesters.
Terms to know
 Germ layers
o Endoderm, Ectoderm, and Mesoderm
o Different parts of the body develop from these layers
 4 membranes aid the development of the embryo
o Amnion
 Turns into the amniotic sac which cushions the embryo from
injury and keeps it most
o A second membrane forms the yolk sac
 Does not contain yolk
 Place where first blood cells and reproductive cells originate
o A third membrane called the allantois
 Forms near the yolk sac
o Chorion
 Surrounds all other membranes
 One side forms finger like projections called chorionic villi
 Blood vessels that form the chorionic villi originate in
the allantois
70
 Placenta
o Chorionic villi and a portion of the uterine lining (endometrium)
form a close-knit structure called the placenta
o Structure where the mother nourishes the embryo. Substance can
diffuse across the placenta but maternal blood and fetal blood never
mix
o The embryo is attached to the placenta by the umbilical cord
(contains 2 arteries and 1 vein)
o A developing placenta secretes the hormone HCG (human
chorionic gonadotropin)
 Stimulates the corpus luteum to continue producing sex
hormones (estrogen + progesterone) to maintain the uterine
lining, stopping menstruation
 As the placenta grows it takes over the maintenance of sex
hormones
 Estrogen + progesterone act in negative feedback mechanism
decreasing the concentration LH + FSH, stopping ovulation
 Lanugo: a layer of soft hair that grows over the skin in the second
trimester
 Labor: Muscles contractions and other events leading up to birth are
called
 Afterbirth: The remains of the placenta, amnion, and uterine lining
expelled shortly after a baby is born
71
FIRST
TRIMESTER
 The most
dramatic changes
occur.
 First 2-3 weeks
the embryo
resembles the
embryo of other
animals
 The embryo
begins to move,
although the
mother cannot
feel it yet

Two weeks after
fertilization
The developing human
is known as embryo
The placenta begins to
develop,
Early in the second
week
Placenta secretes the
hormone HCG
Beginning of 3rd week
 The primary germ
layers developed.
Ectoderm and
Endoderm first,
later the Mesoderm
During the third week
of pregnancy
 The brain, spinal
cord and rest of the
nervous system have
begun developing
(21 days)
 The heart begins to
beat
By the end of the first
month of pregnancy
All the embryonic
membranes have
formed
Arms, legs, eyes, ears
have begun to develop
The fingers and toes
form
First 8 weeks
By the 5th week
6 weeks
8 weeks +
Now called a fetus until
birth. Only 5cm long.
All of its organ systems
have begun to form
72
SECOND
TRIMESTER
By 12 weeks
Fetus’ arms and legs are
developing. 20 buds for future
teeth appear
By week 21
Eyelashes, eyebrows,
fingernails, lanugo have
formed
 Mother’s uterus
enlarges
 Fetus’ heartbeat
can be heard
 Mother may feel
fetus movement
By the end of the
 It can make a fist,
second trimester (6
suck its thumb,
months )
hiccup, kick, curl
its toes
THIRD
TRIMESTER
 Fetus grows
quickly undergoing
changes to allow it
to survive without
the mother
The fetus is about 34cm long
and 900g in weight
Changes
 Fetus can see light and darkness from inside the
mother’s abdominal wall
 It can react to music and loud sounds
 By eight months the fetus’ bones have
hardened, lanugo has disappeared, and body fat
is developing
 The fetus develops fat deposits under its skin
which make it rounded and less wrinkly.
Insulate the body so that it can maintain a steady
body temperature
73
Birth
 Occurs 270 days or 38 weeks after fertilization
 Childbirth is initiated by prostaglandins secreted by fetal membranes
and hormones produced by the both the fetus and mother
 High levels of prostaglandins, oxytocin (posterior pituitary), and
estrogen causes the uterus to contract
o Amniotic sac breaks and amniotic fluid flows out through the
vagina (breaking water)
o Muscles in the cervix and vagina relax
 Enabling them to enlarge and allow the fetus to pass through
 Contractions of the uterus, vagina, and cervix push the fetus
 Afterbirth is expelled shortly after the baby is born
 Following birth
o Newborn’s lungs expand for the first time
o Umbilical cord is cut and tied
 Its arteries and veins close off 30 minutes after birth and
changes in the baby’s blood vessels occur
 Completion of cardiopulmonary and renal circulation
o The newborn’s respiratory and excretory systems soon become
fully functional
74
Section 7.1: Mendel’s Legacy
 1843: entered a monastery in Brunn, Austria
 1851: entered the University of Vienna
 Researched heredity
o Transmission of characteristics from parent
to offspring
 Studied with many plants but most famous for his
work with a species of garden peas called Pisum
sativum
Pea plant characteristics studied by Mendel
 Characteristic: a heritable feature such as flower
color
 Trait: a variant of a characteristic
o Mendel studied 7 characteristics each with
two distinct traits (14 total)
 Mendel’s methods
o Careful control of pollination
 Transfer of pollen from anther
(male) to the ovule in the stigma
(female)
 Self-pollination occurs between the
anther and stigma of one plant
 Cross-pollination is between two
different plants
 Self-pollination was prevented by
Mendel by removing all the anthers
o Cross-pollination was manually controlled
to select for specific traits
stigma
anther
75
Mendel’s Experiments
 True-breeding
(homozygous) P
generation produced
by self-pollination for
several generations
 Always produced
offspring with the
same trait
 First filial generation
produced by crosspollinating P
generation plants
with contrasting
traits
 Same phenotype
(purple)
 Same genotype
 Second filial
generation produced
by allowing F1
generation to selfpollinate
 3:1 phenotype (3
purple 1 white)
 1:2:1 genotype (1
PP, 2 Pp, 1 pp)
(heterozygous)
Mendel’s Results and Conclusions
 Mendel hypothesized that something within the pea plants controlled the
characteristics observed. He called them factors (which are now referred
to as alleles)
 He also hypothesized that each trait was inherited by means of a single or
separate factor
o The offspring receives a single allele from each parent
 And because each characteristic had two different forms, he reasoned that
a pair of characteristics control each trait
76
Mendel’s Laws
Recessive and Dominant Traits
 Certain traits disappeared and reappeared in later generations
 Mendel concluded that one factor may mask or prevent another
factor from having an affect
 Mendel called factors that masked other factors and whose traits
were expressed fully dominant
 Traits that reappeared/were masked he called recessive
 Traits controlled by recessive factors had no observable effect on
appearance when paired with a trait controlled by a dominant
factor
The Law of Segregation
 Paired factors separate during meiosis (formation of gametes)
 Each gamete receives one factor
 When gametes combine during fertilization, the organism gets two
factors for each characteristic
The Law of Independent Assortment
 Independent assortment is the random separation of homologous
chromosomes
 Traits with dominant factors do not necessarily appear together
when tracking two characteristics
 Mendel concluded factors for individual characteristics are not
connected
 Factors separate independently of one another during meiosis
 Only observed for genes located on different chromosomes
77
Independent Assortment
Homologous
chromosomes
Normal gametes
Support for Mendel’s Conclusions
 Most of Mendel’s findings agree with molecular genetics
o The study of the structure and function of chromosomes and genes
 A chromosome is a threadlike structure made up of DNA
 A gene is a segment of DNA on a chromosome (genes control traits)
 Alternative forms of genes on a pair of homologous chromosomes are
called alleles (or Mendel’s factors)
78
Section 7.2: Genetic Crosses
Genotype: the genetic makeup of the organism (alleles inherited)
Phenotype: the appearance of the organism (expression of alleles)
 Phenotype is also influenced by environmental factors such as
nutrition
Homozygous (true-breeding): both alleles are alike (PP, pp)
Heterozygous: alleles are different (Pp)
Monohybrid (2x2)
Dihybrid (4x4)
Single characteristic is tracked
Two characteristics are tracked
Offspring are called monohybrids
Offspring are called dihybrids
Involves the possible combinations of
two alleles from each parent
Involves the possible combinations of
four alleles from each parent
Monohybrid
 Homozygous x Homozygous
o Homozygous dominant is crossed
with homozygous recessive
o 100% chance of heterozygous
genotype (Pp)
o 100% chance of the dominant
phenotype (purple flower)
79
 Homozygous x Heterozygous
o If homozygous dominant
 1:1 genotypic ratio (2 BB : 2 Bb )
 100% chance of the dominant phenotype (black)
o If homozygous recessive
 1:1 genotypic ratio (2 Bb : 2 bb)
 1:1 phenotypic ratio (50% black 50% brown)
 Heterozygous x Heterozygous
o 1:2:1 genotypic ratio (1 BB : 2 Bb : 1 bb)
o 3:1 phenotypic ratio (75% black 25% brown)
 Testcross
o A parent displaying the dominant trait can either be heterozygous or
homozygous for that trait (In the case of complete dominance)
o To find the genotype, the parent with the unknown genotype is crossed
with a homozygous recessive individual
o Possible crosses
 If the offspring all display
the dominant phenotype
then the unknown
individual is homozygous
 If any offspring displays the
recessive phenotype, then
the unknown individual is
heterozygous
80
 Incomplete dominance
o In the case of complete dominance, the
phenotypes of heterozygous and homozygous
dominant individuals are the same
o Incomplete dominance is when the heterozygous
genotype expresses a phenotype that is in
between or intermediate between the dominant
and recessive alleles (blending occurs)
o The genotypic ratio is 1:2:1 (1 RR : 2 Rr : 1 rr)
o The phenotypic ratio is also 1:2:1
Four o’clock flower
 (1 red, 2 pink, 1 white)
 Pink is the intermediate phenotype
 Codominance
o Heterozygous individuals express both alleles of a gene equally (blending
does not occur). Neither allele is dominant nor recessive.
o The MN blood type system is an example of codominance
o The genotypic ratio is 1:2:1 (1 LM LM : 2 LM LN: 1 LN LN )
o The phenotypic ratio is 1:2:1
 (1 M, 2 MN, 1 N)
 MN individuals display both M and N molecules/antigens on the
surface of red blood cells
81
Dihybrid
 Homozygous x Homozygous
o All offspring are heterozygous for both
characteristics
 100% RrYy
o All offspring display the dominant trait
for each characteristic
 100% round, yellow
 Heterozygous x Heterozygous
o 9:3:3:1 phenotypic ratio
 9 round, yellow | 3 round, green | 3
wrinkled, yellow | 1 wrinkled, green
o 9 possible genotypes
Forked-line method
We can break down a dihybrid cross into
two monohybrid Punnett squares. By
multiplying the probabilities for two
monohybrid genotypes of different
characteristics, we get the total probability
for the combined dihybrid genotype. Can
also be applied to the phenotype.
82
Section 8.1: Discovery of DNA
Griffith’s Experiment
 Fredrick Griffith studied Streptococcus pneunomia to try to find a vaccine
o A bacterium that causes lung disease in mammals
 Used two strains of the bacterium in a series of experiments that provided
insight about the nature of hereditary material
 Experiments that killed the mouse:
o Live S cells
o Heat-killed S cells mixed with R cells
 Experiments that did not kill the mouse:
o Heat-killed S cells
o Live R cells
 Griffith concluded that the hereditory factor is transferred from the dead S
cells to the live R cells in a process called transformation
o Transfer of genetic material from one organism to another
S Strain
R Strain
 Virulent (carries the disease
 Nonvirulent (harmless
 Smooth-edged colonies
 Rough colonies
 Surround by a capsule made of
polysaccharides
 Lacks a capsule
83
Avery’s Experiments
 Oswald Avery and his colleagues wanted to know what the transforming agent was in
Griffith’s experiments (DNA, RNA, or Protein)
 Enzymes were used to separately destroy each of 3 the molecules in a heat-killed S cell
o Protease was used to destroy protein
o RNase was used to destroy the RNA
o DNase was used to destroy DNA
 Three experiments were performed, each with one of the molecules missing
 The cells missing DNA did not transform R cells into S cells
 Therefore they concluded that DNA is the hereditary factor responsible for
transformation in bacteria
Hershey-Chase Experiment
 Martha Chase and Alfred Hershey tested wether DNA or protein was the hereditary
material transferred from bacteriophage (virus) to bacteria.
 Radioactive isotopes were used to label the molecules in the phage
o
35
o
32
S was used to label DNA
P was used to label protein
 The labeled phages were separately allowed to infect Escherischia coli (E. coli) bacteria
 Most of the protein was found outside of the bacteria
 They found all of the viral DNA and little of the protein was found inside the cell
and concluded that DNA is the hereditary material in viruses
84
Section 8.2: DNA Structure
 DNA is composed of two chains of nucleotides that wrap around each
other to form a double a helix.
o The structure was discovered by scientists James Watson and
Francis Crick
 DNA Nucleotides
o DNA is a nucleic acid made up of repeating subunits called
nucleotides
o Each full turn of the helix has 10 nucleotide pairs
o The nucleotide is made up of 3 parts
 5 carbon sugar (deoxyribose) (identical in all nucleotides)
 Nitrogenous base (Nitrogen and carbon atoms, accepts
hydrogen ions) (may be any one of 4 different kinds)
 Phosphate group (P atom bonded to four O atoms)
(identical in all nucleotides)
 DNA Bonds
o Nucleotides along each strand are connected by covalent bonds
between the sugar of one nucleotide and the phosphate group of the
next
o Bases on one strand form hydrogen bonds with the bases on the
other strand

2 bonds between adenine and thymine

3 bonds guanine and cytosine
o The base pairs are of uniform length because each two-ringed base
is bonded to a single ringed base
85
Nitrogenous bases
Double ring of carbon and nitrogen
atoms
A&G
Single ring of carbon and nitrogen
atoms
T&C
Complementary bases
 Erwin Chargaff discovered the percentage of adenine is equal to thymine, and
the percentage of guanine is equal to cytosine. This supports the hypothesis that
DNA is a double strand
o If an organism had unequal percentages of A & T and unequal
percentages of G & C, that would support the hypothesis that DNA is a
single strand
 Bases pair by base-pairing rules and pairs of bases are called complementary
bases
 The order of bases on a chain of DNA is called a base sequence
o Opposite strands have the complementary sequences
 Base pairing is important because:
1. Hydrogen bonds help hold the two strands together
2. The complementary nature of DNA helps explain DNA replication (one
strand serves as a template for making a new complementary strand)
86
Section 8.3: DNA Replication
 DNA replications is the process by which DNA is copied before a cell
divides by mitosis, meiosis, or binary fission
 Steps of DNA Replication
1. An enzyme called helicase separates the strands by breaking hydrogen
bonds between bases, allowing the bases to separate as well

The Y-shaped region that results is called the replication fork
2. DNA polymerase enzyme adds the complementary base pairs floating
around freely in the nucleus to each of the original strands

Covalent bonds form between adjacent nucleotides on the growing
strand

Hydrogen bonds form between complementary bases
3. DNA polymerases finish the replication and the result is two separate,
identical DNA molecules that move to new cells in cell division

In each new double helix, one strand is from the original and the
other is new. This type of replication is called semi-conservative
replication.
87
Action at the Replication Fork
 DNA replication occurs in different directions on each strand
Away from the
replication fork
(opposite direction)
Direction of the
replication fork
(unwinding)
 Synthesis on the strand moving away from the fork leaves gaps in the newly
synthesized strand.
o Theses gaps are later joined together by an enzyme called DNA ligase
DNA Errors in Replication
 DNA polymerases repair errors in DNA as well as adding
complementary nucleotides
o They have repair enzymes that proofread DNA
 Mutation: A change in the nucleotide sequence of a DNA molecule
o Some errors, or mutations, escape repair.
o Chemicals and ultraviolet light from the sun can damage DNA
o Some mutations lead to cancer
o Sometimes the changes allow individuals to survive and reproduce
better
o Mutations that affect genes controlling cell division can lead to a
cancerous mass of cells called a tumor
o Studying DNA replication can help with the understanding and
treatment of human cancers
o Mutations in gametes are more significant than in body cells
88
Section 8.4: Protein Synthesis
 Protein synthesis is the mechanism by which genes are expressed and their
function in making proteins that determine traits in organisms
 Genes are segments of DNA that code for a hereditary character.
o Genes direct the production of proteins through an intermediate called
ribonucleic acid (RNA)
 Melanin is a pigment protein whose production is directed by
genes in hair-follicles that determine hair color
 Genetic information flows in 2 steps
o Transcription
 DNA acts as a template for a
RNA
o Translation
 RNA directs assembly of
proteins
 Forming proteins based on genetic
information in DNA carried out by RNA is
called protein synthesis or gene expression
o The is process summarized as: DNA  RNA  protein
 Proteins protect the body against infection (antibodies), and carry oxygen in
the red blood cells (hemoglobin)
DNA
 Contains the sugar
deoxyribose
 Nitrogenous base thymine
complementary to adenine
RNA
 Contains the sugar ribose
 Nitrogenous base uracil
complementary to adenine
 Double-stranded
 Usually single-stranded
 Long length (hundreds of
thousands of genes)
 Short length (about one gene)
89
Types of RNA
tRNA
• Transfer RNA , which transfers amino acids to the ribosome to
make a protein
• Made of many nucleotides linked together
• Three nucleotides are emphasized (anti-codon)
mRNA
• Messenger RNA, a single stranded molecule that carries
intructions from a gene
• Carries the genetic message from the DNA in the nucleus to the
ribosome in the cytoplasm
• Each three-nucleotide sequence (codon) encodes for a specific
amino acid.
rRNA
• Part of the structure of ribosomes (ribosomal RNA)
• Ribosomes are the organelles where protein synthesis occurs
90
Transcription
 The process by which DNA is rewritten into RNA molecules
o Occurs in the nucleus for eukaryotic cells and the DNAcontaining region in prokaryotic cells
1. RNA polymerase binds to a promoter (a specific DNA
nucleotide sequence) and the DNA begins to unwind and separate
2. The RNA polymerase adds free RNA nucleotides complementary
to the DNA template
o ATCGAC (DNA template)  UAGCUG (RNA sequence)
3. Transcription ends when the RNA polymerase reaches a
termination signal (a specific DNA nucleotide sequence) that
marks the end of a gene. The RNA polymerase then transcribes
another gene.
 mRNA, tRNA, and rRNA are all made through this transcription
process
91
The Genetic Code
 Genetic codes is the term for the rules that relate a sequence of nitrogenous
bases in nucleotides corresponds to particular sequence of amino acids.
 Each three-nucleotide sequence in mRNA codes for a specific amino acid
and is called a codon
o There are 64 codons
o Amino acids can have more than one codon, but no codon codes
encodes more than one amino acid
 For example the codons encoding alanine are GCU, GCC,
GCA, GCG
 The genetic code is nearly universal to all life and supports the idea that all
organisms share a common ancestor
 A special codon, AUG, acts as a start codon. It codes for the amino acid
methionine
 Certain sequences DO NOT code for any amino acid. They signal for
translation to end
o UAA, UAG, UGA are stop codons
o The translation of the mRNA sequence UAACAAGGAGCAUCC,
doesn’t produce any amino acid because it starts with a stop codon
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Translation
 mRNA directs the assembly of proteins
o All major types of RNA are involved in translation (mRNA, tRNA,
rRNA)
o Proteins are made of one or many polypeptides, which are amino
acids linked together by peptide bonds
o There are 20 different types of amino acids
o The amino acid sequence determines the shape of the protein. The
shape of the protein is critical to its function
 Steps of Translation
1. INITIATION: tRNA and mRNA (ribosomal subunits) join together. tRNA
has two ends. Enzymes attach an amino acid to one end according to the
genetic code. The other end of tRNA has a three-nucleotide RNA sequence
complementary to mRNA codon called anticodon
o There are 61 anticodons
o tRNA carrying methionine (start codon) will have the amino acid on
one end, and the anticodon UAC on the other end.
 The first amino acid in nearly all polypeptide chains is
methionine, but it may be removed later.
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2. ELONGATION: Polypeptide chain is put together. tRNA with next amino
acid in the sequence pairs its anticodon with the second codon on mRNA.
o The ribosome detaches methionine from the first tRNA. The initial
amino acid then forms a peptide bond with the second.
o The first tRNA then exits and the ribosome moves a distance of one
codon along the mRNA
3. ELONGATION (continued): The growing polypeptide chain continues to
grow as it moves from one tRNA to the amino acid attached to the next
tRNA. The mRNA is moving along the ribosome
o The polypeptide grows one amino acid at a time
4. TERMINATION: The ribosome reaches a stop codon (UGA, UAA, UAG)
and the newly made polypeptide falls off
o There is no anticodon for the stop codons because they do not encode
any amino acid
5. DISASSEMBLY: Translation components fall apart, the last tRNA leaves,
and the machinery is now free to translate the same or another mRNA
o Several ribosomes may translate the same mRNA transcript at the
same time
o In prokaryotes translation can occur even before transcription has
finished. The lack a nuclear envelope
o In eukaryotes, translation occurs only after transcription is
finished
The Human Genome
 The entire gene sequence, 3.2 billion base pairs in the 23 human
chromosomes
 Bioinformatics uses computers to compare different DNA sequences
 There are approximately 30,000 genes in the human genome
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Section 9.1: Chromosomes & Inheritance
 Francis Collins and his colleagues discovered the gene for cystic fibrosis
(CF)
o Jeff Pinard was Collins’ student
 Thomas Hunt Morgan studied the small fruit fly Drosophila
Melanogaster
o He observed they that they have 4 pairs of chromosomes (3
autosomal 1 sex chromosome)
 Females have two X’s and males have an X and Y
Sex Chromosomes and Autosomes
 Sex chromosomes are the chromosomes that contain genes that
determine the gender of an individual
o Humans have 23 pairs of chromosomes. 22 are autosomal and 1
pair are sex chromosomes
 Females have XX and males have XY
o Chicken and moth males have identical sex chromosomes. Females
have different sex chromosomes
o Most plants and some fish lack chromosomes
Sex Determination
 Like other homologous chromosomes, sex chromosomes pair during
meiosis I. The sex chromosomes move on to different cells as meiosis
proceeds
o A sperm can receive either an X or Y chromosome while eggs only
receive the X chromosome. Thus the father determines the sex of
the offspring
o The Y chromosome has the SRY gene that codes for a protein that
causes gonads to develop as testes. Lack of the gene, and by the
extension the protein, causes the gonads to develop as ovaries.
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Effects of Gene Location
 One of Morgan’s students noticed
a male fruit fly that had white eyes
(different from the usual red eyes).
 The white-eyed male cross with a
red-eyed female and all the F1
offspring were red-eyed.
Indicating that the trait was dominant
 The F2 generation then presented with the expected 3:1 phenotypic ratio.
Unexpectedly, however, all the white-eyed flies were male
 Morgan’s Conclusions
o Genes reside on chromosomes
o The gene for eye color is on the X chromosome, and since males
have no homologous X chromosome they are more likely to inherit
the recessive phenotype.
o These traits are known are sex-linked, because the alleles are
found on sex chromosomes. Traits on the X chromosomes are xlinked, and y-linked on the Y chromosome
 The X chromosome is much larger than the Y so there are
significantly more X-linked traits.
o Males that carry the recessive allele on the X chromosome will
exhibit the sex-linked trait.
Linked Genes
 Genes that are inherited together and are always on the same
chromosome are linked genes
 Linked genes are inherited together because there is a small distance
between them on the chromosome, thus decreasing the probability that
they are separated during the genetic recombination (crossing-over) that
occurs in meiosis
 Linked genes DO NOT assort independently
 Sets of linked genes are called linkage groups
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Chromosome Mapping
 The further two genes are the more likely a
cross-over will occur
 The greater the number of recombinant traits,
the further genes are from each other
 Alfred H. Sturtevant made the first
chromosome map for flies
o A chromosome map shows the linear
order of genes on a chromosome
 The cross-over frequency is directly
proportional to the distance between two
genes
 A map unit is defined as a cross-over
frequency of 1%
Mutations
 A mutation is a change in the base nucleotide sequence of a gene or DNA
molecule
 A germ-cell mutation occurs in the gametes
o Affects the offspring
 A somatic-cell mutation occurs in the body cells
o Affects the organism itself, cannot be inherited
o Certain types of skin cancer and leukemia
 Lethal mutations cause death, often before birth
 Some mutations are beneficial
 Mutations can involve and entire chromosome or a single nucleotide
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Chromosome Mutations
Loss of a piece of a
chromosome due to
breakage
Chromosome segment breaks
off, flips around backward,
and reattaches
Ex: GAGACATT is inverted
and becomes GATACAGT
(length does not change)
Piece of one
chromosome
breaks off and
reattaches to a
nonhomologous
chromosome
Nondisjunction
 A chromosome fails to separate from homologue during
meiosis
o One gametes receives and extra copy of the
chromosome and another receives no copies
 Down syndrome is a result of a nondisjunction mutation
where a person receives an extra copy of chromosome 21
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Gene Mutations
Substitution
Point
mutation
A point mutation is any
change that occurs within
a single gene or other
segment of DNA and
involves a single
nucleotide
Insertion
Deletion
Frameshift
mutation
In substitution one nucleotide replaces another (if a
codon is affected, the amino acid can be changed)
In deletion one or more nucleotides are in a gene are lost
In insertion one or more nucleotides are added
 A frameshift mutation is caused by either a deletion or insertion of a
nucleotide and can cause incorrect grouping of remaining codons (makes all
amino acids downstream change)
 A frameshift mutation is more series than a point mutation because it affects
more amino acids and has disastrous effect on protein functions
 Only substitution doesn’t cause a frameshift mutation because the total
number of nucleotides does not change
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Section 9.2: Human Genetics
 The inheritance of genetic traits is studied by analyzing the phenotypes of a
family in a pedigree
o The phenotype is easier to study because you only need to rely on the
appearance of offspring and/or parents in the pedigree
o A pedigree is a diagram that shows how a trait is inherited over many
generations
Pedigree key
 Roman numbers indicate the generation number (I, II, III, IV...)
o The pedigree of cystic fibrosis: an autosomal recessive disease
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Patterns of Inheritance
Autosomal
Dominant
 Traits are autosomal if their genes are
located on the autosomal chromosomes
 Autosomal dominant traits do not
“skip” a generation and appear in at
least one parent of each generation
 Appear in equal proportion for both
sexes
 Each individual with the trait will have
a parent with that trait
 Huntington’s disease, breast cancer,
Marfan Syndrome
Recessive
 Usually skips a generation; an affected
offspring may have one, both, or neither
parent display the trait
 Affected offspring will have the
homozygous recessive genotype (aa).
 Cystic fibrosis, Sickle cell anemia,
Tay-Sachs, Phenylketonuria
Sex-linked
X-linked
 Mostly affects males (however females
can still be affected)
Dominant
 XrY/ XrXr genotype is not affected by
disease
 XRY/XRXr/XRXR genotype is affected
 Located on the X-chromosome
 Eye color in fruit flies
 Most sex-linked traits are recessive
Recessive
 Males cannot be carriers
 XrY/ XrXr genotype is affected by
 A male inherits the X chromosome from
disease
his mother
 XRY/XRXr/XRXR genotype is not
affected
 Hemophilia, Colorblindness
Y-linked
 SRY gene in humans
A Y-linked trait will ONLY appear in
males
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Genetic Traits and Disorders
 Genes have multiple patterns of inheritance and genetic disorders are
diseases or disabling conditions that have a genetic basis
Polygenic Inheritance
 Most human characteristics are polygenic; meaning that they are influenced
by several genes
o Examples are skin color, height, hair color
 Skin color results from the additive effects of three to six genes. The greater
the number of melanin (black pigment) producing alleles per gene, the
darker the skin.
o For example a person with “AaBbCc” genotype would generally have
darker skin than someone with the “aabbcc” genotype. AABBCC
would have the darkest skin.
 This is the final amount of melatonin unexposed to sunlight.
Complex Characters
 Characters that are strongly influenced by the environment as well as genes
 Skin color is bother polygenic (several genes) and complex (affected by
exposure to the sun)
 Height is influenced by an unknown number of genes, nutrition, and disease
 Most breast cancer occurs in individuals with no familial history of the
disease (risk factors include a diet high in saturated fat). However breast
cancer also runs in some families
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Multiple Alleles
 Many genes have more than three alleles

The ABO blood type is controlled by the three alleles IA, IB and i
o IA and IB are codominant (meaning both alleles are expressed in the
phenotype if they genotype is heterozygous
 These alleles encode variants of an enzyme that causes different
sugar molecules to appear on the surface of the red blood cell.
 Heterozygous individuals have both molecules expressed.
o The i allele is recessive to both IA and IB
 i lacks the activity of the enzyme (no sugar molecule is
produced
o Combinations of these alleles produce four different blood types:
 A, B, AB, O
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Incomplete Dominance
 Individual displays a trait that is intermediate between the two parents
(blending occurs), and has the heterozygous genotype
 For example the hair type of Caucasians can either be straight, curly or
wavy. The wavy hair is the heterozygous intermediate between straight and
curly
X-linked Traits
 Pedigrees usually affected many affected males and no affected females
 A male inherits the X chromosome from his mother
 Colorblindness is a recessive X-linked disorder in which an individual
cannot distinguish certain colors (such as red and green)
o Several X-linked genes encode proteins that absorb red and green
light. Colorblindness occurs because a mutation disrupts those genes
and the eye cannot absorb certain colors
Sex-Influenced Traits
 Autosomal traits involved in other complex characters
 Male and females show different phenotypes despite having the same
genotype
 An example is pattern baldness, which is more commonly found in men.
The difference is due to higher levels of testosterone in men, which interacts
with the genotype to produce pattern baldness
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Single-Allele Traits
 A single allele of the gene controls single-allele traits
o More than 200 traits are controlled by single dominant alleles
o Huntington’s disease (HD) is an autosomal dominant conditions
controlled by a single allele
 Symptoms include: forgetfulness, irritability, muscle spasms,
severe mental illness, and death.
 The disease develops around 30 or 40 years of age
 Each affected individual has at least one affected parent. Most
HD patients have already had children when symptoms appear/
Direct DNA testing allows for earlier diagnosis
Detecting Genetic Disease
 Genetic screening is an examination of a person’s genetic makeup
 May involve karyotypes, blood tests for certain proteins, or direct DNA tests
 Chorionic villi sampling: physicians take a sample from cells derived from
the zygote that grow between the mother’s uterus and placenta.
o Occurs between the 8th week and 10th week of pregnancy
 Amniocentesis: Allows physicians to remove some amniotic fluid from the
amnion (sac that surrounds fetus)
o Occurs between 14th and 16th week of pregnancy
 Geneticists use fetal cells obtained through these methods to prepare fetal
karyotypes that might display chromosomal mutations. Allowing the
diagnosis of chromosomal abnormalities before birth
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Important Genetic Disorders
Huntington’s disease (gene HD)
Autosomal dominant on
chromosome 4
Cystic fibrosis (gene CFTR)
Autosomal recessive on
chromosome 7
Sickle cell anemia (gene HBB)
Autosomal recessive on
chromosome 11
Tay-Sachs disease (gene HEXA) Autosomal recessive on
chromosome 15
Phenylketonuria (gene PAH)
Autosomal recessive on
chromosome 12
Breast cancer (gene BRCA1)
Autosomal dominant on
chromosome 17
Hemophilia (gene F8)
X-linked recessive on
chromosome X
Genetic Counseling and Treating Genetic Disease
 The process of informing a person about their genetic makeup
 Phenylketonuria (PKU)
o Causes a lack of an enzyme that converts the amino acid
phenylalanine into the amino acid tyrosine. Resulting in a buildup of
phenylalanine in the body
o Symptoms include sever mental retardation. The treatment is a strict
food regimen for PKU patients to eliminate phenylalanine from their
diets
o Can be detected by means of a blood in the first few days of life
 Cystic fibrosis (CF)
o Thick, sticky mucous builds up and blocks ducts in the pancreas and
intestines and causes difficulty breathing
o Physicians prescribe 45-minute sessions of back and chest pounding
to dislodge the sticky mucous
 Other symptoms prevention measures: insulin injection for diabetes and
injection of missing blood-clotting protein (fibrin) for hemophilia.
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Gene Therapy
 Involves replacing the defective gene; a technique places a healthy copy of
the gene into the cells of a person whose copy is defective.
o Relies on knowing the sequence of nitrogenous bases of a gene
 The functional allele of the gene (such as CFTR) is placed in a virus that is
introduced to the patient’s lungs. The virus infects the cells and brings along
functional genes.
o The improvement only lasts until the functional genes slough off, and
the patient must undergo the procedure again
 Somatic gene therapy: Only the body cells are altered
o An extension of normal medicine
 Germ cell therapy: Eggs or sperm are altered
o Bioethicists (ethical issues in biological research) view germ cell
therapy posing risks and ethical issues because future generations
could change in unpredictable ways
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Section 10.1: DNA Technology
 No two people have the same DNA (except identical twins)
 Only about 0.1% of the human genome varies from person to person, which
scientists can use to identify people based on their DNA
 Uses of DNA technology:
o Identifying human remains
o Determining paternity
o Tracing human origins
o Proving evidence in criminal cases
Non-coding DNA
98% of our genetic makeup (DNA) does not code for any protein. These
regions are called non-coding DNA
 Length polymorphisms are variations in the length of non-coding DNA in
between known genes
 Some length polymorphisms come from short nucleotide sequences that
repeat in tandem, or behind each other called VNTR (variable number
tandem repeats)
o ..CACACA..would be a repeating sequence (VNTR), but
TTTAAACCC would not.
 Number of tandem repeats at different places (loci) in DNA is different for
each individual
 For each of the VNTR loci in a person’s DNA, they will have a certain
number of repeats. By knowing how frequently VNTR occur in the general
population, geneticists can determine how rare a particular DNA profile is.
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Steps in DNA Identification
1. Isolate the DNA and make copies if needed
2. Cut the DNA into segments containing known VNTR areas
3. Sort the DNA by size
4. Compare the unknown sample of DNA to a known sample of DNA
Polymerase Chain Reaction (PCR)
A polymerase chain reaction is a technology to quickly make copies of
DNA. Copies are need because unknown samples are usually acquired in very
small amounts
 Requirements for PCR:
o A template (sequence to be copied)
o Primers
 Artificially made pieces of single-stranded DNA 20-30 nucleotides
long. Primers are complementary to the ends of the template sequence
 Primers bind to DNA during copying
o A supply of the four nucleotides
 Adenine, guanine, cytosine, thymine
o Heat-tolerant DNA polymerase
 Adds the free complementary nucleotides to make a new copy of DNA
 Heating breaks the hydrogen bonds holding the template sequence together,
allowing complementary primers to bond to each strand. Cooling allows the primers
to fully bind and DNA polymerase completes the new copy
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Cutting DNA: Restriction Enzymes
 Restriction enzymes are bacterial proteins that
recognize specific short DNA sequences, and cut
the DNA in or near the sequence
 Some restrictions enzymes leave sticky ends
o Stick ends are DNA overhangs that allow
other complementary pieces of DNA to bind
to cut DNA
Sorting DNA by Size:
Gel Electrophoresis
 Sticky end labeled 2 must be
ACCGGT because it is
complementary to sticky end labeled 1

Gel electrophoresis is a technique used to study DNA fragments, separating them according
to their size and charge

DNA samples cut with restrictions enzymes are placed in wells on a thick gel. An electric
current runs through the gel for a given period of time. DNA fragments are negatively
charged so they migrate towards the positive end of the gel; the smaller fragments migrate
faster, which separates the DNA by size.

DNA is then transferred to a nylon membrane and radioactive probes bind to
complementary DNA. After that, an X-ray film is exposed to the radiolabeled membrane.
The resulting pattern is called a DNA fingerprint
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Recombinant DNA
 Recombinant DNA results when DNA from two different organism is joined.
o Recombinant DNA is possible because all organisms share the same
chemical structure of DNA molecules, differing only in nucleotide
sequence
 The process of altering the genetic material of cells or organism to allow
them to make new substances is called genetic engineering
o An example is scientist encoding a green fluorescent protein (GFP)
with a zebrafish gene to study zebrafish blood vessel growth (the
blood vessels glowed green)
Cloning Vectors
 A clone is an exact copy of a DNA fragment, whole cell, or complete
organism. Cloning is the creation of a genetic duplicate (exact copy).
 Cloning is done by inserting DNA fragments into vectors, which are
DNAs that are inserted into a bacterium or yeast, replicate, and can carry
foreign DNA
o The yeast or bacterium carrying the vector with foreign DNA
reproduces and the vector is copied as well. A colony of cloned
cells that includes the foreign DNA is created.
o Cloning vectors can be plasmids or viruses that infect bacteria.
 Plasmids are small rings of DNA found in some bacterial
cells in addition to the main bacterial chromosome/DNA
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 An application of recombinant DNA is the
production of insulin (the first recombinant DNA
product)
 The human gene for insulin is extracted from DNA
using restriction enzymes
 Plasmids are also cut with restriction enzymes. The
donor gene is joined with the plasmid (vector) with
DNA ligase. It is now recombinant DNA
 The recombinant DNA is insert into a host bacterium
and allowed to reproduce. The bacteria containing the
donor can be identified using probes
Probes
 A strand of RNA, or single-stranded DNA that is labeled with a
radioactive element or fluorescent dye and that can base-pair to specific
DNA.
 The probe for the donor gene in the figure (human insulin gene) is the
mRNA for the gene
 The DNA from the bacteria is transferred onto filter paper. When viewed
under ultraviolet light or exposed to photographic film, the cell clones with
the donor DNA and the attached probe glow, revealing its location.
 After identifying which bacterium received the donor gene, more of the
specific recombinant bacterial clone can be grown.
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