Name: KEY
Unit 10: Immune System
Per. _________
Part 1: Viruses & Bacteria
Virus



what is virus?
retrovirus
cancer and virus
Bacteria
 what is a bacterium?
 identifying bacteria
 reproduction
 adaptation
 importance
 diseases
 antibiotics
Part 2: Infectious Disease & the Immune System
disease
Spread of disease
 food or water borne
ex.
 aire borne
ex.
 contact
ex.
 wound
ex.
 arthropod vectors
ex.
Defenses against disease
 First Line
 Second Line
 Third Line
Allergies/ histamine
Autoimmune Diseases
ex.
Immunity
 Inborne
ex.
 Acquired
 active/ passive
ex.
 natural/ artificial
ex.
Vaccines
 transmission
 treatment
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-Part 1: Viruses & BacteriaVIRUSES
A. What
a.
b.
c.
is a virus
nucleic acid in a protein coat
non-living – does not carry on life processes other than replication and then only in a host cell
viral structure
i. inner core of nucleic acid (DNA or RNA)
ii. outer protein coat called capsid
1. capsid = arrangement of proteins to determine shape of virus and what cells can
be infected
iii. some larger viruses have an envelope
d. attachment to host cell
i. attaches when one of its proteins interlock with receptor site on host cell’s plasma
membrane (like jigsaw puzzle fitting together)
ii. specific process –can only attach to a few kinds of cells due to the shape of their
attachment protein (remember enzyme & hormone activity?)
e. virus injects its nucleic acid  host cell like an injection
f. enters host cell, whose plasma membrane surrounds virus and forms vacuole, virus bursts from
vacuole & release nucleic acid into cell
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B. Retrovirus
a. RNA virus
b. virus makes DNA from RNA by reverse transcriptase (enzyme which makes DNA from RNA),
viral DNA integrated with host chromosomes  provirus
c. if reverse transcriptase is found in humans, it is evidence of infection by a retrovirus
d. HIV – infection of white blood cells (WBC’s)
i. virus infects WBCs
ii. infected WBCs still function normally and do not appear sick, so disease can be
transmitted without even knowing you are infected
iii. while there may be no symptoms for long periods of time, eventually HIV infected people
will get AIDS, because, over time, increasing numbers of WBCs are infected and produce
new viruses.
iv. WBCs gradually are lost as they enters lytic cycle and kills host  decreased WBCs and
decreased ability to fight diseases
C. Cancer and Virus
a. Hepatitis B linked to liver cancer
b. disrupts the normal growth and division of host cells  abnormal growth and tumors
BACTERIA
A. What is bacterium?
 they’re everywhere!!
 they are the oldest life form still living
 very small cell with all structures necessary to carry out
life functions
 antibiotics/penicillin interferes with bacteria’s ability to
make cell wall
B.
Identifying bacteria
a. reaction to Gram Staining
i. reflects differences in cell wall composition
ii. gram positive  purple
iii. gram negative  pink
iv. affected by different antibiotics
b. shapes
c. characteristics of growth patterns
i. spheres (coccus)
i. diplo – paired arrangement
ii. rods (bacillus)
ii. staphylo – resembles clusters of grapes
iii. spirals (spirillum)
iii. strepto – arrangement of chains
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C.
Methods of reproduction
a. Binary fission – mitotic division  2 identical cells
b. Transfer of DNA by:
1.
conjugation : mating process that transfers DNA
2. transduction : transfer from one host bacterium to another by virus
3. transformation: transfer of genes from lysed bacterium to another bacterium
D.
Adaptations
a. diversity
i. obligate aerobes – require oxygen for respiration
ii. obligate anaerobes – killed by oxygen
iii. facultative anaerobes- can live with or without oxygen
b. survival mechanism
i. in unfavorable conditions (extreme conditions), endospores are produced
1. endospores – tiny structures that contain bacerium’s DNA and a small amount of
cytoplasm, encased by a tough outer covering that resists drying out, temperature
extremes, and harsh chemicals
2. bacterium rest in this stage
ii. when conditions become favorable again, endospores germinate and
produce a cell that grows and reproduces
E.
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Importance of Bacteria
a. nitrogen fixation
b. recycling nutrients
c. food and medicine
i. food: pickles, cheese, yogurt
ii. medicine: streptomycin, erythromycin, bacitracin, neomycin
endospores
F.
Diseases caused by bacteria
 Pathogen = organism that causes a disease
Inhibiting Bacterial Growth
1. refrigeration – slows bacterial growth (esp. below 40 oF) 40 oF ~ 140 oF danger zone
2. canning (heating) – kills most
exception: (Clostridium botulinum) Why? Produce endospores
3. salt curing – dehydrates
4. drying – dehydrates
5. radiation – kills on exposure
6. germicidal chemicals
Lister – first to use antiseptic procedures during surgeries
Antibiotics
= drugs that combat disease-causing bacteria by interfering
with various cellular functions
ex. penicillin – interferes with cell wall synthesis
ex. tetracycline – disrupts protein synthesis
ex. sulfa drugs – inhibits cell metabolism

broad-spectrum antibiotics will affect a large number of
bacteria
Antibiotic Resistance
 overuse of antibiotics results in survival of strongest
bacteria, only
Food Spoilage
 most caused by bacteria
5
The Top 5 Disease-causing Bacteria in Food:
Salmonella
 intestinal bacterium typically found in undercooked meats or eggs
 can lead to nausea and fever
 prevented by hand washing, sanitizing food equipment, and cooking to temperature of between 145 oF and
165 oF.
E.




coli
bacterium occurring naturally in animals and humans
transmitted by ingesting contaminated food or water
can lead to diarrhea, however 0157-H7 strain can lead to kidney failure and death
prevented by proper hygiene, cooking ground beef to 155 oF or higher for 15 seconds, and sanitizing food
equipment
Campylobacter
 bacterium causing infectious diarrhea
 recently discovered strain has been linked to Guillain-Barre syndrome, a possibly fatal disease
 found in poultry, contaminated water, or unpasteurized milk
 transmitted through cross-contamination
 prevented by cooking to temperatures of 165 oF or higher, proper hygiene, and proper sanitizing
Listeria
 bacterium found in soil, water, or plant matter
 transmitted by ingesting infected dairy products or undercooked poultry and meats
 can lead to Listeriosis, a potentially severe illness among the elderly and small children
 can also lead to meningitis
 prevented by proper hygiene, thorough cooking and washing, and proper sanitizing
Hepatitis A
 a virus infecting the liver that causes fever, nausea, and muscle aches
 found in the feces of infected humans and spread through poor personal hygiene or contaminated water
 ingesting raw shellfish from contaminated waters can lead to outbreaks
 prevented by good personal hygiene and thorough washing
*Source: Restaurant Business, December 1, 1997
1. How do viruses take over their hosts?
Attaches itself to receptors on cell membrane & inject nucleic acid.
2. What’s the difference between a virus and a bacterium?
Virus- non-living
Bacteria- living
3. Where are bacteria found?
EVERYWHERE!
4. What happens when you overuse antibiotics?
Strongest bacteria survive & reproduce- antibiotics won’t work anymore. (survival of the fittest)
5. When can bacteria be helpful?
Food & medicine.
6
-Part 2: Infectious Disease and the Immune System
disease = a condition in which a system, an organ, or part of an organ is not functioning properly
o hereditary
o environmental
o infections: can be spread from one host to another by a pathogenic organism
The Spread of Diseases – Methods of Infection
1. food-borne/ water-borne
 enter through mouth in contaminated food or
water, or by unsanitary practices
ex. Salmonella SE, E. coli, 0157H7, Listeria
Staphylococcus, botulism – food poisoning
ex. typhoid fever – sewage contamination
- “typhoid Mary” – immune
ex. dysentery – E. coli – sewage contamination
2. air-borne infections (droplet)
 enter through respiratory tract
ex. colds, flu, TB
3. contact infections
 spread by contact with lesions
ex. VD, impetigo, chickenpox, smallpox
4. wound infections
 enter broken skin
ex. staph, strep infections
ex. tetanus
5. arthropod vectors
 disease carried by insects’ feet, bite, feces
ex. bubonic plague/ rat flea
ex. African sleeping sickness/ tsetse fly
ex. malaria/ Anopheles mosquito
ex. Lyme Disease/ deer ticks
Defense Against Disease:
-nonspecific defensesA. First Line
a. skin & perspiration: bacteria-proof if unbroken

b. mucus and hairs or cilia: trap bacteria
c. tears: wash them out
d. stomach acid: HCl destroys most
b,c,d contain lysozymes that destroy bacteria
B. Second Line
= inflammatory response
a. phagocytes: engulf bacteria
- WBC’s = leucocytes + dead bacteria  pus
- macrophage – bigger
b. swelling (from release of histamine at site of injury)
c. fever – stimulates body defenses when moderate; (over 105 oF often lethal)
d. interferon production – inhibits viral reproduction
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C. Third Line: The Immune System
-specific defenses


specific defenses act against one particular pathogen
organs of the immune system include bone marrow, thymus gland, lymph nodes, tonsils, adenoids, and
spleen
antibodies: produced by blood in response to foreign proteins (antigen)
- produced in lymph nodes, spleen, thymus
- two types of lymphocytes (white blood cells of the immune system):
1. T lymphocytes (T cells): produced in bone marrow; mature in thymus
2. B lymphocytes (B cells): produced and mature in bone marrow
- B cells release antibodies; T cells help B cells to produce antibodies
= primary immune system
- B cells react more quickly at second invasion of same bacterium
= secondary immune response
- T cells involved in graft and transplant rejections
Allergies
= inappropriate reactions to otherwise harmless antigens

8
symptoms caused by release of histamines
Autoimmune Diseases
= lymphocytes attack cells of body
ex. multiple sclerosis, systemic lupus, rheumatoid arthritis
Types of Immunity:
I. Inborn Immunity/ Species Immunity
II. Acquired Immunity
natural – having disease
ex. measles
Active
(you produce antibodies)
artificial – by injection
ex. DPT vaccine
natural - colostrum
(antibodies ingested in milk)
Passive
(you are given antibodies)
artificial – injection of antibodies produced elsewhere
ex. tetanus antitoxin (short-term)
Development of Vaccines
Jenner 1796 smallpox vaccination
Pasteur’s anthrax vaccine
 1876: immunized healthy sheep;
inoculated with anthrax
vaccinated sheep remained healthy
Polio Vaccines
1952 - Jonas Salk developed vaccine from weakened (attenuated) polio virus
1957 - Albert Sabin developed oral vaccine
Antibiotics
1935 – sulfa drugs/ sulfanilamide
WWII
1928 – penicillin – Fleming
 first antibiotic; from blue-green mold
 also: tetracycline, amoxicillin, etc.
Use of antibiotics should be limited:
1. side effects
2. bacterial resistance
ex. V.D. and penicillin
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AIDS = Acquired Immunodeficiency Syndrome
 recognized as a disease in 1981: has killed more than 300,000 Americans; 15,000/day infected
 caused by a retrovirus – HIV (Human Immunodeficiency Virus)
 targets helper T cells of immune system and reproduces large numbers of new viral particles
 immune system successfully fights off the virus for 2 to 10 years or more
 person becomes vulnerable to “opportunistic infections” and cancers
 most common transmission of HIV:
1. sexual intercourse (any kind) with infected person
2. sharing syringes and needles with infected person
Treatments:
1. vaccine in the works but difficult due to rapid rate of evolution of virus (mutation)
2. drugs – 3 antivirals keep viral load low for long periods of time
*currently no cure
Unit Recap:
VIRUS
 capsid- protective outer coat
 contain DNA or RNA
 infect cells by binding to receptor sites (specific shape)
IMMUNE SYSTEM
 immunity: ability of the body to resist disease-causing organisms
 immune systems protect us against pathogens (disease-causing organisms)
 antigens (proteins on pathogen) stimulates an immune response
 antibodies (from WBC in our body) fight the antigens
 organ transplant rejection happens when your immune system attacks the transplanted organ
 allergic reactions occur when your body has immune responses to substances that are usually harmless
 passive vs. active immunity: passive- receive antibodies from other organisms; active- produce own
antibodies
 vaccination: dead or weakened microbes to trigger antibody production (active immunity)
White Blood Cells
 phagocytes: engulf bacteria, viruses, and other foreign organisms
 lymphocytes: produce antibodies
o produced when antigen enter the body
 AIDS is caused by HIV
o destroys the body’s immune system
Must, must, MUST know for the unit…
1. pathogen disease-causing organism
2. antigen foreign protein (on bacteria or virus)
3. antibodies fights pathogens (from our bodies)
4. how your body fight pathogens
antibodies produced in body in response to antigen. Memory cells produced to remember the pathogens
for when they invade again.
5. how vaccines work weak/dead virus injected so your body makes antibodies. Enough to activate
immune response, not enough to get you sick.
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Practice:
1. One similarity between cell receptors and antibodies is that both
1. are produced by nerve cells
3. slow the rates of chemical reactions
2. are highly specific in their actions
4. are involved in digestion
2. An individual who has had chicken pox rarely gets the disease again. This situation is an example of
1. biological control
3. active immunity
2. negative feedback
4. passive immunity
3. Which phrase does not describe a way the human body responds to fight disease?
1. destruction of infectious agents by white blood cells
2. production of antibodies by white blood cells
3. increased production of white blood cells
4. production of pathogens by white blood cells
4. A person with AIDS is likely to develop infectious diseases because the virus that causes AIDS
1. destroys cancerous cells
3. increases the rate of antibody production
2. damages the immune system
4. increases the rate of microbe destruction
5. Which substances may form in the human body due to invaders entering the blood?
1. nutrients
2. vaccines
3. antibodies
4. red blood cells
6. Which statement best describes an immune response?
1. It always produces antibiotics.
2. It usually involves the recognition and destruction of pathogens.
3. It stimulates asexual reproduction and resistance in pathogens.
4. It releases red blood cells that destroy parasites.
7. If a human system fails to function properly, what is the most likely result?
1. a stable rate of metabolism
3. a change in the method of cellular respiration
2. a disturbance in homeostasis
4. a change in the function of DNA
8. Which statement does not identify a characteristic of antibodies?
1. They are produced by the body in response to the presence of foreign substances.
2. They may be produced in response to an antigen.
3. They are nonspecific, acting against any foreign substance in the body.
4. They may be produced by white blood cells.
9. Which disease damages the human immune system, leaving the body open to certain infectious agents?
1. flu
2. AIDS
3. chicken pox
4. pneumonia
10. What usually results when an organism fails to maintain homeostasis?
1. Growth rates within organs become equal.
2. The organism becomes ill or may die.
3. A constant sugar supply for the cells is produced.
4. The water balance in the tissues of the organism stabilizes.
11. Which activity is not a response of human white blood cells to pathogens?
1. engulfing and destroying bacteria
2. producing antibodies
3. identifying invaders for destruction
4. removing carbon dioxide
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12. In some individuals, the immune system attacks substances such as grass pollen that are usually harmless,
resulting in
1. an allergic reaction
2. a form of cancer
3. an insulin imbalance
4. a mutation
13. People with AIDS are unable to fight multiple infections because the virus that causes AIDS
1. weakens their immune systems
3. attacks muscle tissue
2. produces antibodies in their blood
4. kills pathogens
14. Feedback mechanisms are best described as processes that help
1. reduce hormone levels to below normal in the blood
2. destroy hormones in the blood
3. directly control muscle contraction in the leg
4. keep body conditions near a normal, steady state
15. Allergic reactions are most closely associated with
1. the action of circulating hormones
3. immune responses to usually harmless substances
2. a low blood sugar level
4. the shape of red blood cells
16. Microbes that enter the body, causing disease, are known as
1. pathogens
2. antibodies
3. enzymes
4. hosts
17. Many vaccinations stimulate the immune system by exposing it to
1. antibodies
2. enzymes
3. mutated genes
4. weakened microbes
18. The diagram below represents one possible immune response that can occur in the human body.
The structures that are part of the immune system are represented by
1. A, only
2. A and C, only
3. B and C, only
4. A, B, and C
19. Antibody molecules and receptor molecules are similar in that they both
1. control transport through the cell membrane
2. have a specific shape related to their specific function
3. remove wastes from the body
4. speed up chemical reactions in cells
20. Which transplant method would prevent the rejection of tissue after an organ transplant?
1. using organs cloned from the cells of the patient
2. using organs produced by genetic engineering to get rid of all proteins in the donated organs
3. using organs only from pigs or monkeys
4. using an organ donated by a close relative because the proteins will always be identical to those of
the recipient
13
Base your answers to questions 21 through 24 on the passage below.
Avian (Bird) Flu
Avian flu virus H5N1 has been a major concern recently. Most humans have not been
exposed to this strain of the virus, so they have not produced the necessary protective
substances. A vaccine has been developed and is being made in large quantities. However,
much more time is needed to manufacture enough vaccine to protect most of the human
population of the world.
Most flu virus strains affect the upper respiratory tract, resulting in a runny nose
and sore throat. However, the H5N1 virus seems to go deeper into the lungs and causes
severe pneumonia, which may be fatal for people infected by this virus.
So far, this virus has not been known to spread directly from one human to another.
As long as H5N1 does not change to another strain that can be transferred from one
human to another, a worldwide epidemic of the virus probably will not occur.
21. State one difference between the effect on the human body of the usual forms of flu virus and the
effect of H5N1. [1]
usual flu- causes runny nose & sore throat
H5N1- causes severe pneumonia
22. Identify the type of substance produced by the human body that protects against antigens, such as the
flu virus. [1]
antibodies
23. State what is in a vaccine that makes the vaccine effective. [1]
weak/ dead virus
24. Identify one event that could result in the virus changing to a form able to spread from human to human.
[1]
mutation
June ’09 #56 ~ 59
25. Many people become infected with the chicken pox virus during childhood. After recovering from chicken
pox, these people are usually immune to the disease for the rest of their lives. However, they may still be
infected by viruses that cause other diseases, such as measles.
Discuss the immune response to the chicken pox virus. In your answer, be sure to include:
• the role of antigens in the immune response [1]
• the role of white blood cells in the body’s response to the virus [1]
• an explanation of why recovery from an infection with the chicken pox virus will not protect a person from
getting a different disease, such as measles [1]
• an explanation of why a chicken pox vaccination usually does not cause a person to become ill with chicken
pox [1]
 antigens causes an immune response (makes body produce antibodies)

attacks and destroys virus/ make antibodies against virus

the antibodies are specific to chicken pox virus- won’t work on any other virus

dead/ weakened virus
June ’05 #56
14
Base your answers to questions 26 through 28 on the information below.
Proteins on the surface of a human cell and on a bird influenza virus are represented in the diagram below.
26. In the space below, draw a change in the bird influenza virus that would allow it to infect this human cell.
[1]
27. Explain how this change in the virus could come about. [1]
mutation
_________________________________________________________________________________
28. Identify the relationship that exists between a virus and a human when the virus infects the human. [1]
parasite/ host (parasitic)
pathogen/ host (pathogenic)
June ’08 #53~ 55
Base your answers to questions 29 through 31 on the passage below.
A normally healthy 35-year-old woman was found to have a severe intestinal infection
usually seen in much older and sicker patients in hospitals. Because of so many cases like hers,
some doctors became alarmed that the organism responsible could spread rapidly and cause
unusually severe illnesses and some deaths. Scientists suspect that the cause is a mutated
form of an organism that has a resistance to some of the most common treatments.
29. Since it is difficult to cure an infection caused by this organism, it might be easier to prevent these
infections by using a vaccine. Identify the specific material a vaccine would have to contain to prevent future
infections. [1]
dead/ weakened organism
30. Explain how this vaccine would prevent future infections. [1]
vaccine stimulates antibody production
31. The mutated form of this type of organism could result from a change in a molecule within one member of
the original population. Identify the molecule. [1]
DNA
Jan ’10 #43~ 45
15
Base your answer to question 32 on the information below and on your knowledge of biology.
Until the middle of the 20th century, transplanting complex organs, such as kidneys,
was rarely successful. The first transplant recipients did not survive. It was not until
1954 that the first successful kidney transplant was performed. Success with transplants
increased as research scientists developed techniques such as tissue typing and the use of
immunosuppressant drugs. These are drugs that suppress the immune system to prevent
the rejection of a transplanted organ. In
2002, there were nearly 15,000 kidney transplants performed in the United States
with a greater than 95% success rate.
32. Describe the relationship of the immune system to organ transplants and the use of immunosuppressant
drugs to prevent the rejection of a transplanted organ. In your answer be sure to:
• state one way the immune system is involved in the rejection of transplanted organs [1]
• explain why the best source for a donated kidney would be the identical twin of the recipient [1]
• explain why immunosuppressant drugs might be needed to prevent rejection of a kidney received from a
donor other than an identical twin [1]
• state one reason a person may get sick more easily when taking an immunosuppressant drug [1]

antibodies cause organs to be rejected (immune system recognizes transplanted organs as
foreign and attacks it)

same DNA (genetic makeup)/ same proteins

stop immune system from attacking donated organ (block production of antibodies)

weakens immune system
Aug ’07 #55
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