The immune system exam q Flashcards
(21 cards)
Describe how HIV is replicated
4 marks
Attachment proteins on HIV attach to receptors on T helper cells
RNA and enzymes enter the t helper cell
Reverse transcriptase converts RNA to DNA
Viral proteins and enzymes are produced
Virus particles are then assembled and leave the cell
4 max
Use your knowledge of phagocytosis to explain how an ADC cell destroys a tumour cell
3 marks
ADC is engulfed by the cell
Lysosomes fuse with the vesicle containing ADC
Lysosymes break down ADC to release the drug
Some of the antigens found on the surface of tumour cells are also found on the surface of healthy human cells.
Use this information to explain why treatment with an ADC often causes side effects
2 marks
1 ADC binds to the healthy cells
2 Causing death/ damage to healthy cells
or
2 May cause damage to organ systems/ organs
Suggest and explain two further investigations that should be done before this ADC is tested on human breast cancer patients.
( already been tested on mice)
2 marks
- Test on other mammals to check for side effects
- Test on healthy humans in small doses to check for side effects
-Investigate different concentrations of ADC to find suitable/safe
dosage;
Describe how the human immunodeficiency virus (HIV) is replicated once
inside helper T cells (TH cells)
4 marks
- RNA converted into DNA using reverse transcriptase;
- DNA incorporated/inserted into (helper T cell) nucleus
- DNA transcribed into (HIV m)RNA;
- (HIV mRNA) translated into (new) HIV/viral proteins
Use the information given to evaluate the use of BSCT to treat HIV
infections. 4 marks
( Evaluating practise )
- Only one transplant/BSCT needed (shown by patient Q)
- Would not need (daily) ART (16 months after BSCT);
Agaisnt
Do not know if BSCT alone would be effective;
Chemotherapy/radiotherapy is toxic/harmful/has side-effect
Don’t know if it would work in all people
Might not be long term
Describe how a phagocyte destroys a pathogen present in the blood 3 marks
1 Engulfs;
2. Forming vesicle/phagosome and fuses with lysosome
3. Enzymes digest/hydrolyse;
Give two types of cell, other than pathogens, that can stimulate an immune
response 2 marks
- Cells from) other organisms/transplants;
- Abnormal (cells);
What is the role of the disulfide bridge in forming the quaternary structure
of an antibody? 1 mark
Joins two different polypeptides
Explain how HIV affects the production of antibodies when AIDS develops in a person 3 marks
- Less/no antibodies are produced
-HIV destroys T helper cells
-No B cells stimulated to divide by mitosis in order to differentiate and form plasma cells
Ms disadvantages for a certain drug, analysis of the effects of a drug..
-No stats test done
-Only one person/limited number of people/ limited ethnic groups considered
-No control group
-Unknown side effects/ limited knowledge of the side effects
-Only shows results after a certain period of time
-
In Europe, viruses have infected a large number of frogs of different species. The
viruses are closely related and all belong to the Ranavirus group.
Previously, the viruses infected only one species of frog.
(a) Suggest and explain how the viruses became able to infect other species
of frog. 2 marks
- Mutation in the viral DNA/ RNA/ genetic material
-Altered the tertiary structure of the attachment proteins/ antigens
MUTATIONS always link to TERTIARY structure
Determining the genome of the viruses could allow scientists to develop a vaccine Explain how.
2 marks
(The scientists) could identify the proteome;
They could then identify possible antigens to use in the vaccine
Describe how the B lymphocytes of a frog would respond to vaccination
against Ranavirus.
You can assume that the B lymphocytes of a frog respond in the same way
as B lymphocytes of a human.
Do not include details of the cellular response in your answer.
B cell binds to (viral) specific/complementary
receptor/antigen;
Accept B cell forms antigen-antibody complex
2. Cell divides by mitosis;
3. Plasma cells release/produce (monoclonal) antibodies (against the
virus)
4. Plasma cells produce memory cells
What is a monoclonal antibody?
1 mark
Antibodies with the same tertiary structure/ produced from cloned plasma cells
Give one example of monoclonal antibodies used in a medical treatment 1 mark
Carries drug to specific antigens
or
Blocks antigens/ receptors on cells
Describe the role of antibodies in producing a positive result in an ELISA test.
4 marks
- (First) antibody binds
2+3. Second antibody with the enzyme attaches to first antibody
(indirect ELISA test). - (Substrate/solution added) and colour changes
Describe and explain the role of antibodies in stimulating phagocytosis.
Do not include details about the process of phagocytosis
3 marks
Are markers
Antibodies cause clumping/ aggulation or they attract phagocytes
The scientists hypothesised that memory B cells had formed in the mice
180 days after the 3rd injection.
Suggest and explain a practical method the scientists could use to test this
hypothesis.
Inject vaccine (again)/meningitis antigen
(Memory cells present if) faster/more rapid production/higher
concentration antibody (than 1st injection)
Add enzyme attached to (second) antibody against memory cell
Colour change shows memory cells present;
When a person is bitten by a venomous snake, the snake injects a toxin into the person. Antivenom is injected as treatment. Antivenom contains
antibodies against the snake toxin. This treatment is an example of passive
immunity.
Explain how the treatment with antivenom works and why it is essential to use passive immunity, rather than active immunity.
Antivenom antibodies bind to the toxin and (causes) its destruction
Active immunity would be too slow/slower
During vaccination, each animal is initially injected with a small volume of
venom. Two weeks later, it is injected with a larger volume of venom.
Use your knowledge of the humoral immune response to explain this
vaccination programme.
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