CELLS: HIV and Viruses

Question 1

What does HIV stand for?

Answer 1

Human Immunodeficiency Virus

Question 2

What is HIV?

Answer 2

A virus that affects the immune system.

Question 3

If untreated, what can HIV progress to?

Answer 3

AIDS.

Question 4

What is AIDS?

Answer 4

Acquired immune deficiency syndrome.

Question 5

Briefly, what is AIDS?

Answer 5

A condition that progresses from HIV, where the immune system deteriorates and eventually fails.

Question 6

What causes AIDs?

Answer 6

Untreated HIV

Question 7

What does the capsid of HIV enclose?

Answer 7

Two single strands of RNA and some enzymes.

Question 8

Give an example of one of the enzymes enclosed within the capsid of HIV:

Answer 8

Reverse transcriptase.

Question 9

What is reverse transcriptase?

Answer 9

An enzyme found within the capsid of HIV that catalyses the production of DNA from RNA.

Question 10

What group of viruses does HIV belong to?

Why is this?

Answer 10

Retroviruses.

Due to the presence of reverse transciptase inside of its capsid, meaning it has the ability to make DNA from RNA.

Question 11

Draw a HIV particle:

Answer 11

Question 12

Why are helper T-cells important in the immune system?

Answer 12

They send chemical systems that activate phagocytes, cytoxic T-cells and B-cells.

Without enough helper T-cells, the rest of the immune response can not begin.

Question 13

When do people with HIV develop AIDS?

Answer 13

When the helper T-cells numbers in their body reach a critically low level.

Question 14

What is contained within the core of HIV?

Answer 14

Genetic material and some proteins.

Question 15

What is the capsid?

Answer 15

The outer coating of protein surrounding a HIV particle.

Question 16

What is the outer coating of protein surrounding HIV known as?

Answer 16

A capsid.

Question 17

What is the extra outer layer on a HIV virus called?

Answer 17

An envelope.

Question 18

On a HIV particle, what is the envelope?

Answer 18

The extra outer layer.

Question 19

In HIV, what is the envelope made of?

Answer 19

The membrane stolen from the cell membrane of a previous host cell.

Question 20

What do attachment proteins help HIV to do?

Answer 20

Helps HIV attach to the host help T-cell.

Question 21

What is found on the envelope of the HIV particle?

Answer 21

Attachment protiens.

Question 22

What can attachment proteins also be called?

Answer 22

Envelope proteins.

Question 23

How does HIV replicate?

Answer 23

1. Attachment protein attaches to receptor on host helper T-cell
2. Capsid released into cell = uncoats + releases RNA into cytoplasm
3. Reverse transcriptase makes complementary DNA strand
4. Double stranded DNA is made + inserted into human DNA
5. Host cell enzymes make viral proteins from viral DNA found in human DNA
6. Viral proteins assembled into new viruses which bud from cell

Question 24

Latency period

Answer 24

Time after HIV infection where a person won’t experience symptoms.

Question 25

Where does HIV replicate?

Question 26

When does HIV move to aids?

Answer 26

When helper T-cell counts falls below a certain level

Question 27

What are the initial symptoms of AIDs?

Answer 27

Minor infections of mucous membranes

Recurring respiratory infections

Question 28

What can develop during the late stages of AIDs?

Answer 28

Toxoplasmosis of the brain

Candidiasis of respiratory system

Question 29

How do antibiotics kill bacteria?

Answer 29

Interfer with metabolic reactions.

Particularly targeting bacterial enzymes and ribosomes.

Question 30

Why can’t antibiotics work for viruses?

Answer 30

• Viruses don’t have own enzymes and ribosomes, so use human ones
• Antibiotics can’t inhibit as don’t target human processes

Question 31

What are used to treat viruses?

Answer 31

Antiviral drugs target the few virus-specific enzymes

Question 32

Is there a cure for HIV?

Answer 32

No, but antiviral drugs can be used to slow down progression.