HIV

Question 1

1. Describe the structure of the human
   immunodeficiency virus (HIV)

Answer 1

RNA genome; which is contained in a protein capsid; there is also the enzyme Reverse transcriptase; Around the outside is a lipid viral envelope; That has specific attachment proteins on the surface.

Question 2

2. Describe how HIV is replicated after it has
   entered a human cell.

Answer 2

Reverse transcriptase enzyme uses HIV RNA to make a DNA copy; HIV DNA is joined to host cell’s DNA; HIV DNA is now used to make HIV RNA and HIV capsid proteins and reverse transcriptase enzymes; using the hosts ribosomes; These proteins are then Assembled into the new virus particles; and Budding off from membrane of host cell completes the production of HIV particles.

Question 3

3. Which cells does HIV target?

Answer 3

Helper T-cells

Question 4

4. How does HIV target helper t-cells?

Answer 4

The attachment proteins on HIV are complimentary to the specific CD4 receptors found most frequently on helper T-cells. The protein capsid fuses with the cell-surface membrane and the RNA and enzymes enter the cell.

Question 5

5. How does HIV infection cause AIDS (acquired immune deficiency syndrome)

Answer 5

When the replicated virus is released from the cell it destroys the helper T-cell. The viruses go on to infect more helper T-cells which leads to a reduction in the number of helper T-cells.

Question 6

6. How does the destruction of helper T-cells
   cause the death of people with HIV?

Answer 6

When another infection occurs there are Not enough T-cells to activate B-cells which would lead to antibody production; This means the person is unable to kill pathogens that cause infectious diseases.

Question 7

7. Drugs that inhibit the action of HIV enzymes do not destroy HIV, but slow down the development of AIDS. Explain how.

Answer 7

Person infected with HIV has HIV DNA in their DNA; So new HIV particles still made; the drug would inhibit HIVs reverse transcriptase; so slows the replication of HIV; Therefore stopping the destruction of more infected T cells; So immune system continues to work and AIDS does not develop;

Question 8

8. What is AIDS?

Answer 8

Acquired Immune Deficiency Syndrome, caused by the destruction of many helper T-cells by HIV

Question 9

9. Why are antibiotics ineffective against
   viruses?

Answer 9

Antibiotics work on bacterial structures such as the cell wall, 70s ribosomes or enzymes which viruses do not have.