2.4 Cell recognition and the immune system pt 2 Flashcards
(16 cards)
Describe the structure of a HIV particle (5)
Lipid envelope
RNA
Reverse transcriptase
Capsid
Attachment protein
Describe the replication of HIV in helper T cells (7)
- HIV attachment proteins attach to receptors on helper T cell
- Lipid envelope fuses with cell-surface membrane, releasing capsid into cell
- Capsid uncoats, releasing RNA and reverse transcriptase
- Reverse transcriptase converts viral RNA to DNA
- Viral DNA inserted / incorporated into helper T cell DNA (may remain latent)
- Viral protein / capsid / enzymes are produced
a. DNA transcribed into HIV mRNA
b. HIV mRNA translated into new HIV proteins - Virus particles assembled and released from cell (via budding)
Explain how HIV causes the symptoms of acquired immune deficiency syndrome (AIDS) (3)
● HIV infects and kills helper T cells (host cell) as it multiplies rapidly
○ So T helper cells can’t stimulate cytotoxic T cells, B cells and phagocytes
○ So B plasma cells can’t release as many antibodies for agglutination & destruction of pathogens
● Immune system deteriorates → more susceptible to (opportunistic) infections
● Pathogens reproduce, release toxins and damage cells
Explain why antibiotics are ineffective against viruses (2)
● Viruses do not have metabolic processes (eg. do not make protein) / ribosomes
● Viruses do not have bacterial enzymes / murein cell wall
What is a monoclonal antibody?
What is a monoclonal antibody?
● Antibody produced from genetically identical / cloned B lymphocytes / plasma cells
● So have same tertiary structure
Explain how monoclonal antibodies can be used in medical treatments
● Monoclonal antibody has a specific tertiary structure / binding site / variable region
● Complementary to receptor / protein / antigen found only on a specific cell type (eg. cancer cell)
● Therapeutic drug attached to antibody
● Antibody binds to specific cell, forming antigen-antibody complex, delivering drug
Explain how monoclonal antibodies can be used in medical diagnosis
● Monoclonal antibody has a specific tertiary structure / binding site / variable region
● Complementary to specific receptor / protein / antigen associated with diagnosis
● Dye / stain / fluorescent marker attached to antibody
● Antibody binds to receptor / protein / antigen, forming antigen-antibody complex
Explain the use of antibodies in the ELISA (enzyme-linked immunosorbent assay) test to detect antigens (direct elisa)
- Attach sample with potential antigens to well
- Add complementary monoclonal antibodies with enzymes attached → bind to antigens if present
- Wash well → remove unbound antibodies (to prevent false positive)
- Add substrate → enzymes create products that cause a colour change (positive result)
Explain the use of antibodies in the ELISA (enzyme-linked immunosorbent
assay) test to detect antigens (sandwich elisa)
- Attach specific monoclonal antibodies to well
- Add sample with potential antigens, then wash well
- Add complementary monoclonal antibodies with enzymes attached → bind to antigens if present
- Wash well → remove unbound antibodies (to prevent false positive)
- Add substrate → enzymes create products that cause a colour change (positive result)
Explain the use of antibodies in the ELISA test to detect antibodies (indirect elisa)
- Attach specific antigens to well
- Add sample with potential antibodies, wash well
- Add complementary monoclonal antibodies
with enzymes attached → bind to antibodies if
present - Wash well → remove unbound antibodies
- Add substrate → enzymes create products that
cause a colour change (positive result)
Suggest the purpose of a control well in the ELISA test
● Compare to test to show only enzyme causes colour change
● Compare to test to show all unbound antibodies have been washed away
Suggest why failure to thoroughly wash the well can result in a false positive
in the ELISA test
● Antibody with enzyme remains / not washed out
● So substrate converted into colour product
Discuss some general ethical issues associated with the use of vaccines and
monoclonal antibodies
● Pre-clinical testing on / use of animals - potential stress / harm / mistreatment
○ But animals not killed & helps produce new drugs to reduce human suffering
● Clinical trials on humans - potential harm / side-effects
● Vaccines - may continue high risk activities and still develop / pass on pathogen
● Use of drug - potentially dangerous side effects
Suggest some points to consider when evaluating methodology relating to
the use of vaccines and monoclonal antibodies
● Was the sample size large enough to be representative?
● Were participants diverse in terms of age, sex, ethnicity and health status?
● Were placebo / control groups used for comparison?
● Was the duration of the study long enough to show long-term effects?
● Was the trial double-blind (neither doctor / patient knew who was given drug or placebo) to reduce bias?
Suggest some points to consider when evaluating evidence and data
relating to the use of vaccines and monoclonal antibodies
● What side effects were observed, and how frequently did they occur?
● Was a statistical test used to see if there was a significant difference between start & final results?
● Was the standard deviation of final results large, showing some people did not benefit?
● Did standard deviations of start & final results overlap, showing there may not be a significant difference?
● What dosage was optimum? Does increasing dose increase effectiveness enough to justify extra cost?
● Was the cost of production & distribution low enough?
Give one example of using monoclonal antibodies in a medical treatment.
Targets/binds/carries drug/medicine to specific cells/antigens/receptors
OR
Block antigens/receptors on cells;
