2.2.2 - Viruses

Question 1

General structure of a virus.

Answer 1

Acellular
Capsid made from capsomeres
Lipid envelope makes it easier for viruses to pass from cell to cell.

Question 2

How do you classify viruses?

Answer 2

Based on their genetic material.

Question 3

What happens to the genetic material in DNA viruses?

Answer 3

DNA converted to more viral DNA and RNA for protein synthesis.

Question 4

Example of a DNA virus?

Answer 4

Lambada phage (non-enveloped)

Question 5

Example of an RNA virus?

Answer 5

Ebola (enveloped)
Tobacco Mosaic virus (non-enveloped)

Question 6

What happens to the genetic material in RNA retroviruses?

Answer 6

A single strand of RNA causes the synthesis of reverse transcriptase. This in turn synthesises the viral DNA. This viral DNA is inserted in the host cells DNA before being transcribed into RNA to produce proteins.

Question 7

Example of an RNA retrovirus?

Answer 7

HIV (enveloped)

Question 8

What is positive sense ssRNA?

Answer 8

is the equivalent of RNA made from coding/sense strand DNA and can be used directly to produce proteins.

Question 9

What is negative sense ssRNA?

Answer 9

is the equivalent of RNA made from non-coding/antisense strand DNA and therefore will not produce the correct proteins if used.

Question 10

Describe the life cycle of a retrovirus.

Answer 10

A single strand of RNA causes the synthesis of reverse transcriptase.
This then synthesis the viral DNA.