hiv

Question 1

Structure of hiv virus

Answer 1

Core = genetic material (RNA) and the
enzyme reverse transcriptase, which are needed for viral replication.

Capsid = outer protein coat

Envelope = extra outer layer, made out of membrane taken from the host’s cell

Protein Attachments = On the exterior
of the envelope to enable the virus to attach to the host’s helper T cell. membrane.

Question 2

How is hiv replicated

Answer 2

1. Glycoprotein molecules on the virus surface bind to CD4 receptors on the surface of T helper cells. This allows the envelope surrounding the virus to fuse with the T helper cell membrane.
2. The capsid is released into the cell where it releases the RNA and reverse transcriptase
3. Reverse transcriptase is used to make DNA from the HIV RNA template
4. The DNA is inserted into the cell’s DNA which gets replicated when cells replicate
5. DNA used to make HIV RNA and proteins at host ribosomes
6. Virus particles are assembled which bud off from the cell membrane and go on to infect other cells

Question 3

Transmission of HIV

Answer 3

•Having unprotected sex with an infected person.
•Close contact with an infected person’s blood e.g sharing of needles for drug use.
•Use of infected blood in a blood transfusion.
• Mother to child - a mother with HIV giving birth to a child (shared through the placenta) or a child drinking the mothers milk - this is knowns as vertical transmission. Babies must be tested at 18 months as it takes time for the virus to replicate and be detectable.