Lecture 6

Question 0

What are the two stages of growth in synchronous cultures of viruses?

Answer 0

Eclipse phase

Maturation phase

Question 1

Describe the tree basic steps of a virus’ life cycle

Answer 1

1. They attach and penetrate the host cell
2. They uncoat themselves releasing the nucleic acid and allowing protein synthesis to occur.
3. Then they reassemble and exit

Question 2

Describe the eclipse phase in a virus’ life cycle

Answer 2

Low amounts of parental infectious material are present.
Genome replication has been initiated
Duration is minutes perhaps hours

Question 3

Describe the maturation phase of a virus

Answer 3

Viral material accumulates in the cell or surrounding medium

Cells infected with lytic viruses can continue to produce indefinately

Question 4

What are the three types of viral infection?

Answer 4

Productive
Abortive
Restringent or restrictive

Question 5

What is productive infection?

Answer 5

Entry by a virus into a permissive cell which is followed by virion formation

Question 6

What is abortive infection?

Answer 6

Entry into a non-permissive cell which does not result in virion formation

Question 7

What does influenza do if abortive infection occurs?

Answer 7

It releases an enzyme to escape from the cell

Question 8

What is restringent or restrictive infection?

Answer 8

Cell is transiently permissive and a few virus are produced

Question 9

What is the antireceptor if the infleunza virus?

Answer 9

Haemaglutinin

Question 10

What is tropism?

Answer 10

The turning of all or part of an organism in a particular direction in response to an external stimuli

Question 11

Is attachment energy dependent?

Answer 11

No

Question 12

Is uptake energy dependent?

Answer 12

Yes

Question 13

What is uncoating of a virus?

Answer 13

A term applied to events after penetration of a host cell