5.7 The human immunodeficiency virus

Question 1

Describe the structure of HIV

Answer 1

-Lipid envelope
-Attachment proteins
-Capsid
-RNA
-Reverse transcriptase

Question 2

How does HIV replicate?

Answer 2

1. Attachment protein attaches to receptor molecule on T-helper cell
2. Viral RNA is released into the cell’s cytoplasm
3. Reverse transcriptase is used to make a complementary strand of DNA from viral RNA template
4. Double-stranded DNA produced and inserted into the human DNA
5. Host cell enzymes uses to make viral proteins
6. Viral proteins assembled into new viruses

Question 3

How does HIV cause the symptoms of AIDs

Answer 3

• HIV attacks T-helper cells.
  -immune system cannot stimulate B cells to produce antibodies or cytoxic T cells
• body cannot produce an adequate immune response and becomes susceptible to other infections or cancers

Question 4

What does ELISA test stand for

Answer 4

enzyme linked immunosorbant essay

Question 5

Describe the process of an ELISA test

Answer 5

• Apply the sample to a surface to which all the antigens in the sample will attach
• Wash the surface to remove any unattached antigens
  -Add the antibody that is specific to the antigen
• Wash the surface to remove excess antibody
  -Add a second antibody with an enzyme attached that binds with the first antibody
  -Add the substrate of the enzyme
  The formation of an ES complex will cause colour to be released showing a positive result

Question 6

What are antibiotics ineffective against viral diseases

Answer 6

• Antibiotics work by inhibiting the production of murein cell walls in bacteria
  -Viruses don’t contain murein cell walls
• Viruses rely on host cells to carry out metabolic processes
  -Antibiotics can’t reach them