HIV

Question 1

What is HIV?

Answer 1

A virus which infects and kills T-helper cells, leading to the deterioration of the immune system (AIDS)

Question 2

When is AIDS developed?

Answer 2

When T-helper cell count falls below a certain level

Question 3

Stages of HIV infection —> AIDS

Answer 3

Initial infection means HIV replicates rapidly inside host Th cells (flu like symptoms)
Latency period lasting years where replication stops
Millions of virus is released after causing Th cell number to rapidly fall and AIDS develops

Question 4

HIV structure

Answer 4

RNA + reverse transcriptase enclosed in a capsid
Enclosed in envelope with attachment proteins

Question 5

HIV = RNA

Answer 5

Genetic material needed to replicate virus inside Th cells

Question 6

Reverse transcriptase

Answer 6

An enzyme needed for dna replication inside virus

Question 7

Capsid

Answer 7

Protein that encloses genetic material and reverse transcriptase

Question 8

Envelope

Answer 8

Composed of phospholipids stolen from cell membrane of a T helper cell

Question 9

Attachment proteins

Answer 9

The antigens on the virus which attaches to cell surface of Th cell

Question 10

Why do virus replication take place in cells?

Answer 10

Has no ribosomes to synthesise protein compartments of a new virus

Question 11

Step 1 of virus replication

Answer 11

Attachment proteins attach to cell surface membrane of a Th cell

Question 12

Step 2 of virus replication

Answer 12

Capsid is released into cell’s cytoplasm and the RNA released into cytoplasm from inside capsid

Question 13

Step 3 of virus replication

Answer 13

Enzyme reverse transcriptase synthesises complementary DNA strands which is incorporated into human T helper cell DNA code

Question 14

Step 4 of virus replication

Answer 14

The virus dna inserted will encode for synthesis of viral proteins such as the capsid, attachment protein etc using ribosomes, endoplasmic reticulum and enzymes from host cell

Question 15

Step 5 of virus replication

Answer 15

Using synthesised virus compartments, many viruses are assembled causing cell to burst then be released into blood

Question 16

Development of AIDS

Answer 16

As more and more Th cells die, more serious infections become an issue such as tuberculosis and rare forms of cancer or parasite infections