HIV/ AIDS

Question 1

Why are viruses (in general) difficult to destroy?

Answer 1

• Because viruses replicate inside of host cells, making it difficult to destroy the virus without harming the host cells.

Question 2

Why are antibiotics ineffective against viruses?

Answer 2

• Because viruses have no cell wall -like bacteria do- so cannot be destroyed by antibiotics (antibiotics work by causing damage to the cell wall.)

() - extra info for clarification.

Question 3

What is HIV’s structure?

Answer 3

• Has RNA and enzyme, reverse transcriptase within a capsid.
• Has a lipid envelope
• Has attachment proteins attached to the lipid envelope.

Diagram in Yousaf notes

Question 4

What is the “capsid” in HIV and what does it do?

Answer 4

• Capsid: protein coat around genetic material/ reverse transcriptase.
• FUNCTION: protects viral genome/ genetic material.

Question 5

What do the attachment proteins in HIV do?

Answer 5

• Allows the HIV to bind to specific proteins found on host cell (ie. Helper T cell’s) membrane.

Question 6

What is the function of “reverse transcriptase” in HIV?

Answer 6

• Reverse transcriptase is an enzyme which uses HIV RNA to make a DNA copy.

Question 7

What is the lipid envelope in HIV, where does it come from?

Answer 7

• Extra outer layer of virus, made out of membrane taken from host cell’s membrane.

Question 8

What are the stages of HIV replication in Helper T cells?

Answer 8

1.) HIV attaches to membrane proteins on surface of helper T cells.
2.) Phospholipid envelope fuses with plasma membrane of cell, injecting RNA/ reverse transcriptase into cell.
3.) Cytoplasm of cell: reverse transcriptase uses RNA to make viral double-stranded DNA.
4.) mRNA (from viral double stranded DNA) is transcribed and helper T cell starts to create viral proteins to make new viral particles.

Diagram in Yousaf notes.

Question 9

How does HIV cause the symptons of AIDS?

Answer 9

• HIV virus replicates in helper T cells, so many helper T cells are damaged that this affects normal functioning of immune system
• Helper T cells destroyed by virus, host unable to produce adequate immune response to other pathogens. Could lead to severe infections/ cancer.
• The destruction of the immune system leads to death.

Question 10

True or False

The HIV virus will directly cause someone to die.

Answer 10

• False.
• It is the destruction of the immune system that leads to death, rather than HIV directly.

Question 11

True or False

A patient who has HIV and a patient who has AIDS are the same.

Answer 11

• FALSE!
• Said to have HIV when virus has infected you, said to have AIDS when so many helper T cells have been destroyed by HIV replication that it interferes with normal functioning of immune system.