Title: IB Biology Review Immune System Immune System Vocab Pathogen
1IB Biology Review
2Immune System Vocab
- Pathogen
- An organism or virus that causes a disease
- Antigen
- Any foreign macromolecule (either proteins,
polysaccharides or structures on the surface of
bacteria) that triggers an immune response - Antibody
- Antibodies are proteins that bind to particular
antigens and mark them for elimination from the
body - Antibiotics
- Any substance that is able to kill or inhibit a
microorganism such as bacteria
3Passive versus Active Immunity
- Passive immunity is due to the acquisition of
antibodies from another source - Such as
- when a developing fetus acquires antibodies from
its mother - when they are artificially injected into a person
-
- Active immunity is when antibodies are produced
by the person themselves after his or her immune
system is triggered by antigens
4Immune System Vocab cont.
- Virus
- An infective agent consisting of a protein coat
surrounding an RNA or DNA core - Are not cells and do not possess membranes or
organelles. - They cannot manufacture their own proteins and
must invade living cells to take over their
protein production machinery - Leucocytes
- White blood cells
- Phagocytic leucocytes
- Specialized white blood cells that engulf
foreign/invading pathogens and destroy them
5Different Types of Leucocytes
- The only ones we need to know are monocytes and
macrophages, and lymphocytes
6Why are antibiotics effective against bacteria,
but not viruses?
- Most antibiotics dont kill bacteria
- Antibiotics disrupt their reproduction (binary
fission) by preventing formation of the bacterial
cell wall in the daughter cells (a part of the
cells metabolism) - Since viruses arent cells and dont produce cell
walls, antibiotics are not effective against them
7What are the different components of the immune
system?
- Skin
- Mucous membranes
- Phagocytic leukocytes
- Antibodies
8Skin and Mucous Membranes
- These are a form of external defense preventing
pathogens from entering the body - Skin forms a physical barrier
- Mucous membranes surround invading pathogens
- Body senses excess mucous, induces coughing
- Coughing expels the mucous and the trapped
pathogen
9Phagocytic Leucocytes
- A type of white blood cell
- Float around the body in blood
- Phagocyte surrounds the pathogen by endocytosis
- A vacuole containing the pathogen travels to a
lysosome - The membranes of the vacuole and lysosome fuse
- Digestive enzymes in the lysosome destroy the
pathogen - The pathogen debris is released by exocytosis
10Phagocytic Leucocyte Diagram
11Antibodies
- Proteins that recognize one kind of antigen
- Similar to enzymes (lock and key)
- Lock and key called epitope
- React by binding to the antigen
- Destroys antigen
- Or
- Inactivates antigen
12Antibody Production
- Pathogen is in the body
- Phagocytic leucocytes called macrophages ingest
the pathogens - Phagocytes present the antigens from the
pathogens on their cell surface. - T-helper cells (another type of leucocyte that is
specific to that antigen) bind to the antigen
presented by the macrophages and are
activated/stimulated - Meanwhile, B-cells bind to the antigen, and
present the antigen as the phagocytes did
13Antibody Production cont.
- The activated T-helper cells then bind to B-cells
and activate them - This triggers the B-cells to undergo mitosis to
form memory cells and plasma cells - Short-lived Plasma B-cells secrete antibodies
quickly that neutralize the pathogen - Memory B-cells stay in the blood for a long time
and enable a more rapid response by the immune
system if the same pathogen invades in the future
14HL Only Monoclonal Antibodies
- Monoclonal antibodies
- large quantities of a single type of antibody
- produced in a laboratory
- Hybridoma cell
- memory B cell fused with a tumor cell
- divides uncontrollably, producing a large amount
of antibodies
15HL Only Monoclonal Antibody Production
- 1. Antigens that correspond to a desired antibody
are injected into an animal - 2. B-cells producing the desired antibody are
harvested - 3. Tumor cells are obtained from another source
(tumor cells grow and divide endlessly) - 4. B-cells are fused with tumor cells, producing
hybridoma cells that divide endlessly, providing
the desired antibodies - 5. The hybridoma cells are cultured and the
antibodies they produce are extracted and
purified
16HL Only Application of Monoclonal Antibodies
Rabies Treatment
- Rabies usually causes death in humans before the
immune system can control it. - Injecting monoclonal antibodies when a person
gets infected will control the virus - At the same time, the person's body begins making
its own antibodies - Triggers two-fold immune response
- Passive through injection
- Active through bodys production
17HL Only Application of Monoclonal Antibodies
Malaria Diagnosis
- 1. Monoclonal antibodies are made to bind to
antigens in malarial parasites - 2. A test plate is covered with antibodies
- 3. The sample is left on the plate long enough
for malaria antigens (if present) to bind to
antibodies - 4. The sample is rinsed off
- Any bound antigens are detected using more
monoclonal antibodies with attached
color-changing enzyme
18HL Only Challenge and Response, Clonal
Selection, and Memory Cells
- B-cells make antibodies
- The immune system can make 1015 different types
of antibodies (but not all at once) - A few of each type of B-cell are produced and
they wait until the body is infected with an
antigen - When this occurs, they multiply to form many
clones - This is called clonal selection
- A clone of B-cells can produces large amounts of
antibodies quickly and give immunity to a disease - Only after the immune system is challenged by a
disease - This is called the challenge and response system
19Vaccination
- A weakened or dead version of a pathogen is
injected into the body, causing the immune system
to mount a primary response - This results in the production of B memory cells
- The B-cells "remember" the antibodies to produce
in response to the pathogen - When the real pathogen strikes, a secondary
response occurs, aided by the memory cell
production of pathogen-specific antibodies - This response is much stronger than the primary
response and prevents any ill effects
20HL Only Benefits and Dangers of Vaccines
- Benefits
- prevent disease and epidemics
- results in a healthier society
- reduces long-term medical costs
- speed up the body's response to a future disease
by memory B-cells - Dangers
- possible allergic reactions
- danger of side-effects
21HIV and the Immune System
- HIV virus kills Helper T-cells
- Helper T-Cells tell B-cells there is a pathogen
- Immune system cannot mount an effective defense
against invading pathogens - Patients then succumb to secondary infections
22Blood Clotting
- Damaged cells in the blood vessel release
compounds called clotting factors - These factors trigger the formation of the
enzyme thrombin - Thrombin catalyzes the conversion of soluble
fibrinogen in the blood to the fibrous protein
fibrin - Fibrin forms threads which create an interwoven
net - Platelets and blood cells get caught in the net
and plug up the wound
23Blood Clotting Diagram
241. Which is not true of active immunity? (1
mark)
IB Exam Question
- A. It can be produced by exposure to a disease
causing organism. - B. It can be produced artificially.
- C. It can be produced by a virus.
- D. It can be transferred via the colostrum.
- Correct answer D
- If youve never heard of it, its probably a
trick question!
252. Describe how human skin and mucous membranes
act as barriers to pathogens.(4 marks)
IB Exam Question
- To receive full marks, responses must have two
answers for each. - Skin
- lower pH / acid to keep bacteria from growing /
chemical barrier - fatty acids / waxes antimicrobial
- physical barrier to prevent entry / dry skin
inhibits bacterial growths - bacteria on skin / mucous membranes prevent other
bacteria from growing - antimicrobial / lysozyme in sweat and saliva
(mucous membrane) to keep bacterial growth in
check - Mucous membranes
- mucous traps bacteria / sticky / mucus slightly
acidic i.e. vagina - cilia sweep mucous up to be swallowed to kill
bacteria - contain macrophages / phagocytes
263. Outline how phagocytic leucocytes ingest
pathogens in the blood and in body tissues.
IB Exam Question
- The phagocytic cell surround the pathogen by
endocytosis - A vacuole containing the pathogen travels to a
lysosome and the membranes of the vacuole and
lysosome fuse - Digestive enzymes in the lysosome destroy the
pathogen - The pathogen debris is released by exocytosis
274. Which of the following represents the correct
sequence of events when the body is responding to
a bacterial infection?
(1 mark)
IB Exam Question
- I. Antigen presentation by macrophages
- II. Activation of B-cells
- III. Activation of helper T-cells
- A. I, II, III
- B. I, III, II
- C. III, II, I
- D. II, III, I
- Correct answer B
285. Explain antibody production.
IB Exam Question
- A vaccine is injected into body
- This vaccine contains killed / weakened pathogen
or fragments of pathogens - Phagocytic leucocytes called macrophages ingest
the pathogens and present the antigens from the
pathogens on their cell surface. - Helper-T cells (another type of leucocyte that is
specific to that antigen) bind to the antigen
presented by the macrophages and are
activated/stimulated - Meanwhile, B-cells bind to the antigen, and
present the antigen as the T cells did - The activated T-helper cells then bind to B-cells
and activate them - This triggers the B-cells to undergo mitosis to
form memory cells and plasma cells - Short-lived Plasma B-cells secrete antibodies
quickly that neutralize the pathogen - Memory B-cells stay in the blood for a long time
and enable a more rapid response by the immune
system if the same pathogen invades in the future
296. Which type of cell is responsible for
secondary immune responses to a pathogen?
(1 mark)
IB Exam Question
- A. Cytotoxic T-cells
- B. Phagocytes
- C. Macrophages
- D. Memory cells
- Correct answer D
30HL Only 7. Outline the principles of challenge
and response, clonal selection, and memory cells
as the basis of immunity.
IB Exam Question
- B-cells make antibodies
- The immune system can make 1015 different types
of antibodies (but not all at once) - A few of each type of B-cell are produced and
they wait until the body is infected with an
antigen - When this occurs, they multiply to form many
clones this is called clonal selection - A clone of B-cells can produces large amounts of
antibodies quickly and give immunity to a
disease, only after the immune system is
challenged by a disease - This is called the challenge and response system
318. Which type of immunity usually results from
vaccination? (1 mark)
IB Exam Question
- A. active, natural
- B. active, artificial
- C. passive, natural
- D. passive, artificial
- Correct answer B
329. Discuss the benefits and dangers of
vaccination.
(8 marks)
IB Exam Question
- Benefits 5 max
- prevent disease
- eliminate diseases like smallpox
- prevent epidemics
- healthier society
- reduce medical cost
- disease free cattle / more food
- Dangers 3 max
- allergic reactions / anaphylactic shock
- weakened virus becomes virulent / causes the
disease - harmful side-effects
3310. Which curve shows the response of the immune
system to a vaccine, followed by an infection?
(1 mark)
IB Exam Question
34HL Only 11. Describe the production of
monoclonal antibodies along with one use of them
in diagnosis and one use in treatment.
IB Exam Question
- Monoclonal antibodies - large quantities of a
single type of antibody, produced using the
procedure outlined below. - 1. Antigens that correspond to a desired antibody
are injected into an animal. - 2. B-cells producing the desired antibody are
extracted. - 3. Tumor cells are obtained from another source
(tumor cells grow and divide endlessly). - 4. B-cells are fused with tumor cells, producing
hybridoma cells that divide endlessly, providing
the desired antibodies. - 5. The hybridoma cells are cultured and
antibodies they produce are extracted and
purified.
35HL Only 11. Describe the production of
monoclonal antibodies along with one use of them
in diagnosis and one use in treatment. cont.
IB Exam Question
- Treatment of rabies
- Rabies usually causes death in humans before the
immune system can control it. - Injecting monoclonal antibodies when a person
gets infected will control the virus and at the
same time, the person's body begins making its
own antibodies. - Diagnosis of malaria
- 1. Monoclonal antibodies are made to bind to
antigens in malarial parasites. - 2. A test plate is covered with antibodies.
- 3. The sample to be tested is left on the plate
long enough for malaria antigens (if present) to
bind to antibodies. - 4. The sample is rinsed off and any bound
antigens are detected using more monoclonal
antibodies with attached color-changing enzyme.
3612. Outline the effect of HIV on the immune
system.
IB Exam Question
- The HIV virus results in the death of Helper
T-cells - Therefore, the immune system of the infected
individual cannot mount an effective defense
against invading pathogens - Patients can then succumb to secondary infections
3713. Describe the process of blood clotting.
IB Exam Question
- Damaged cells in the blood vessel release
compounds called clotting factors - These factors trigger the formation of the
enzyme thrombin - Thrombin catalyzes the conversion of soluble
fibrinogen in the blood to the fibrous protein
fibrin - Fibrin forms threads which create an interwoven
net. Platelets and blood cells get caught in the
net and plug the open cut
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