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PATHOGENS & THE
IMMUNE SYSTEM!!!
TERMS TO KNOW
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11.
Virus
Bacteria
Infectious disease
Noninfectious disease
Lytic cycle
Lysogenic cycle
Autoimmune diseases
Active immunity
Passive immunity
Jenner
Pasteur
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21.
Koch’s Postulates
Immune Response
HIV
T cells
B cells
Allergies
Epidemiologist
Culture medium
Inoculation
Incubation
Obj. 1 – Properties, size, & role of
viruses (p. 434-435)
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Virus – segments of nucleic acids contained in a
protein coat
20 nm to 250 nm (1 nm = 0.00000004 in.)
Replicate by infecting cells and using the cell to
make more viruses
Cause disease in many impact
Are NOT alive…

Do not grow, do not have homeostasis, do not
metabolize
Little Assassins: What are Viruses?
Obj. 1, cont.
Contain a protein coat (capsid)
 Can contain DNA or RNA, but not both
 Many contain a membrane (envelope)
surrounding the capsid
 Viruses come in many shapes
 Bacteriophage – a virus that infects bacteria
 Virus is Latin for poison

Study of Viruses
Obj. 2 – Reproduction of viral
particles (p. 436 – 437)
Rely on living cells (host cells) for
replication
 Must infect a host cell (either through tiny
tears or by “injecting” its DNA into the
host cell – T4 bacteriophage)
 Either through lytic cycle or lysogenic cycle
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How Viruses Work
5 Steps of Replication
1.
2.
3.
4.
5.
Attachment
Injection of genetic material
Making new parts
Assembly of parts
Release of new parts
AIMAR
Obj. 3 – Lytic & lysogenic cycle
(p. 436 – 437)
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Lytic Cycle – viral infection, replication,
and cell destruction
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Lysogenic Cycle – infect a cell, but do
not make new viruses…when cell divides
the virus divides also…to cause a problem
the virus has to enter the lytic cycle
Lytic Cycle
1
2
4
3
5
Obj. 4 – Common human viral and
bacterial diseases (p. 440-447)
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Tetanus
Food Poisoning
Tuberculosis
Whooping Cough
Spinal Meningitis
Impetigo
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Small pox
Chicken pox
Colds
Influenza
AIDS
Mumps
Rabies
Herpes
Hepatitis
Warts
VIRAL DISEASES
Viruses Throughout History
BACTERIAL DISEASES
BACTERIAL SHAPES
VIRUSES
VIRUSES, CONT.
Obj. 5 – How do bacteria cause
disease? (p. 447 – 448)
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Simply…bacteria are in competition with your
body for the resources that you need to live
Obj. 15 – Jenner and Pasteur
(p. 931)
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Edward Jenner, English Doctor….
 Invented vaccine
 Infected own son with cow pox (a mild form
of small pox)
 Son didn’t contract small pox
 Cow pox triggered immune system to create
an immunity against small pox
Obj. 15, cont.
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Louis Pasteur
 Pasteurization
 Disproved spontaneous generation
 Said “life came from life”
 Boiled broth to kill microorganisms
Obj. 16 – What is an epidemiologist?
(p. 457)
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A scientist who studies the causes and controls
of disease outbreaks.
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Involved in preventing disease outbreaks and in
stopping outbreaks that do occur spreading.
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Work for CDC, FBI, etc.
Influenza of 1918
Vaccines & Treatment of Viruses
Obj. 17 – Inoculation & Incubation
of culture medium
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Culture medium – either a broth or an agar
with nutrients added to it to aid in the growth of
microorganisms.
Inoculation – referred to as a streak or stab
(putting microorganisms in a nutrient agar or
broth so they can grow)
Incubation – usually 24 – 48 hours at a
temperature of 20º C or 37º C.
Inoculation Technique
Heat loop
Inoculation
Inoculation Broth
Inoculation Slant
Agar Deep
Agar Plate
Streak Plates
Finished Product
Obj. 18 – Koch’s Postulates (p. 930)
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The pathogen must be found in an animal with
the disease and not in a healthy animal.
The pathogen must be isolated from the sick
animal and grown in a laboratory culture.
When the isolated pathogen is injected into a
healthy animal, the animal must develop the
disease.
The pathogen should be taken from the
second animal and grown in a laboratory
culture. The cultured pathogen should be the
same as the original pathogen.
Obj. 6 – Infectious v. Noninfectious
diseases (p. 924)
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Infectious disease - Any disease caused by
the presence of pathogens in the body
 Easily spread from one person to another
or from one body part to another
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Non-Infectious disease - One that does
not spread
 Rheumatoid arthritis
Mutations in Viruses
Obj. 7 - How is disease spread?
 People – Direct contact
 Touching
 Kissing
 Sexual
 Object
contact
– food poisoning
 Air, Soil and Water
 Vectors – insects: malaria
Polio Panic
Pathogen – disease causing
organisms
 Virus
 Bacteria
 Fungi
 Protozoans
Obj. 10 – Immune response
(p. 926 – 929)
Immunity - Building up resistance
 Immunity occurs when system
recognizes a foreign substance and
responds by production of special
lymphocytes which produce antibodies
 After recovery, if infected again, won’t
get sick because defense mechanisms are
in place
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Obj. 8 – T cells and B cells (p. 927 – 929)
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Both are white blood cells
Regulated by helper T cells
B cell response – defense that aids the removal of
extracellular pathogens
 B cells
 Stay in lymph nodes & organs
 Mature in bone marrow
T cell response – destruction of intracellular pathogen by
cytotoxic T cells
 Both lymph, organs & circulation
 Occur in thymus gland (located in lower neck &
thorax)
 Act directly against certain pathogens
Obj. 9 – Specific v. Nonspecific (p. 924-929)
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Nonspecific – always present, fights off
anything foreign to the body.
 2 lines of defense (1 outside, 1 inside)
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Specific – body has been exposed to
disease before (immunity to chicken pox
once you have already had the disease)
Obj. 9, cont.
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1st line of nonspecific defense
 Mucous membranes – traps it before it can enter
the body
 Skin – acts as a physical barrier
 Sweat – contains lysozyme (which digest
bacterial walls)
2nd line of nonspecific defense
 Inflammatory response
 Temperature response
 Proteins
 White blood cells
Obj. 9, cont.
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Temperature response
 Disease causing bacteria don’t grow well
at high temperatures
 Normal body temperature 37º C (98.6º F)
 > 39º C (103º F) – dangerous
 >41º C (105º F) - fatal
Obj. 9, cont.
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Inflammatory
response
Obj. 9, cont.
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Protein complement system
 About 20 different proteins circulate in the blood
and became active when they encounter certain
pathogens by attaching to the surface of proteins
and damaging plasma membrane.
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Interferons
 Protein is released by cells infected with virus
which causes nearby cells to produce an enzyme
that prevents viruses
White blood cells – patrol the bloodstreamwait to attack the pathogen
Neutrophils – engulf bacteria, then release
chemicals that kill bacteria, can also squeeze
between cells in the walls of capillaries to attack
pathogens.
 Macrophage – ingest & kill bacteria and clear
dead cells & other debris, travel through the body
in lymphatic systems and & between cells,
concentrated in particular organ (spleen and lungs)
 Natural killer cells – attack cells infected with
pathogens, puncture cell membrane, water rushes
into infected cell which swells & burst (body’s
defense against cancer)
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Obj. 9, cont.
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SPECIFIC RESPONSE
White Blood Cells – produced in bone marrow and
circulate in the blood and lymph nodes
Macrophage – consume pathogens and infected
cells
Cytotoxic (killer) T cells – attack & kill infected
cells
B cells – label invaders for later destruction by
macrophages
Helper T cells – activate cytotoxic T cells & B cells
Obj. 9, cont.
Infected cell has an antigen (substance that
triggers an immune response) of an
invader on its surface
 White blood cells are covered with
receptor proteins that respond to infection
by binding to specific antigens on the
surfaces of the infecting microbes
 They recognize and bind to antigens that
match their particular shape.
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Obj.11 – Active v. Passive immunity
(p. 930 – 932)
Immunity – resistance to a particular
disease
 Active immunity - immunity that you get
because you have been exposed to a
disease
 Passive immunity – immunity that you
get because of a vaccine
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Obj. 11, cont.
 Vaccine
– immunity producing
substance formed from
weakened, dead or parts of
pathogens/antigens.
Obj. 12 – HIV (p. 934 – 935)
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HIV is transmitted when the body fluids of an
infected individual are passed on to an uninfected
individual by direct contact or contaminated
objects.
Breaks down immune system, so can no longer
fight off disease
 Hides in Helper T cells
People w/HIV, then AIDS suffer from two rare
problems.
 Pneumosystis carinii – protozoan infections of
lungs
 Kaposi’s sarcoma - cancer
Obj. 13 – Allergies (p. 926)
 Occur
when antigens bind to mast
cells.
 Activate mast cells which release
histamines.
 Histamines
produce sneezing, runny
eyes & nose
Common Antigens that cause allergies
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Foods
Dust
 Milk, eggs
Antibiotics
 Penicillin
Cosmetics
Pollen
Molds
Microbes
Chemicals in plants – poison ivy
Obj. 14 – Autoimmune diseases
(p. 933)
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A disease in which the immune system starts
attacking body cells as if they were pathogens.
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Affect organs and tissues in different parts of
the body.
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Graves disease, Multiple sclerosis (MS),
Rheumatoid arthritis, Systemic lupus
erythematosus (SLE), Type I diabetes
Some Autoimmune Diseases
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Rheumatoid Arthritis – exact cause is unknown, but
clear the immune system is involved.
 Involves inflammation of joint, swelling, pain
& loss of function.
Rheumatic Fever – happens when
streptococcus bacteria causes a disease known as
strep throat.
 If left untreated, the immune system produces
antibodies that destroy bacteria.
Multiple sclerosis – result of destruction by
immune system of special cells that surround
nerve fibers and permit rapid impulse
transmission.
Autoimmune diseases, cont.
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Lupus – exact cause unknown, although it is certain
that both environment & genetic factors are involved.
 Believed a genetic pre-disposition to the disease
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Symptoms include:
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Achy joints, 100°F + fever, Arthritis, Prolonged or
extreme fatigue, Skin rashes, Anemia, Kidney
disorders
Factors that trigger Lupus:
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Infections, Antibiotics, Ultra-violet lights, Extreme
stress, Hormones
AUTOIMMUNE DISEASES
Understanding Viruses: Part 2
Chapter 20 & 40 Vocabulary Quiz
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An agent that causes a disease is a __________.
The process in which two organisms exchange
genetic material is __________.
The four step guide for identifying specific
pathogens is called __________ __________.
A non living, infectious particle composed of a
nucleic acid and a protein coat is a __________.
A __________ is a protein that reacts to a specific
antigen or that inactivates or destroys toxins.
A protective response of tissues affected by
disease or injury, characterized by redness,
swelling, and pain is an _____ _____.
Chapter 20 & 40 Vocabulary Quiz
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In bacterial viruses, the cycle of viral infection,
replication, and cell destruction is called the
__________ cycle.
A substance that can inhibit the growth of or kill
some microorganisms is called a __________.
A virus that infects a bacteria is a __________.
An __________ is a substance that stimulates an
immune response.
Chapter 20 & 40 Vocabulary Quiz
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An agent that causes a disease is a pathogen.
The process in which two organisms exchange
genetic material is conjugation.
The four step guide for identifying specific
pathogens is called Koch’s Postulate.
A non living, infectious particle composed of a
nucleic acid and a protein coat is a virus.
An antibody is a protein that reacts to a specific
antigen or that inactivates or destroys toxins.
A protective response of tissues affected by
disease or injury, characterized by redness,
swelling, and pain is an inflammatory response.
Chapter 20 & 40 Vocabulary Quiz
7.
8.
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10.
In bacterial viruses, the cycle of viral infection,
replication, and cell destruction is called the
lytic cycle.
A substance that can inhibit the growth of or
kill some microorganisms is called an
antibiotic.
A virus that infects a bacteria is a
bacteriophage.
An antigen is a substance that stimulates an
immune response.