Viruses Flashcards

1
Q

What are the basic components of a virus?

A

Genome - contains DNA or RNA.
Capsid - made up of capsomeres.
Nucleocapsid = genome + capsid.

The nucleocapid +/- an envelope is known as a virion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 7 stages of a viral lifecycle?

A
Attachment.
Penetration.
Uncoating.
Replication.
Assembly.
Maturation.
Release.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 3 ways in which viral penetration can occur?

A

Viral translocation:
> Virus translocates across the plasma membrane.
> Naked viruses only.

Surface fusion:
> Viral envelope fuses with the plasma membrane.
> Enveloped viruses only.
> pH independent process.

Receptor mediated endocytosis:
> Naked & enveloped viruses.
> pH dependent process.
> Virion binds to cell receptor > endocytosis > fusion with lysosome > decreased pH leads to uncoating & release into cytoplasm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What enzyme is needed for the transcription of DNA viruses?

A

DNA-dependent RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the aim of transcription?

A

To form mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What enzyme is needed for the transcription of SS (-) RNA or DS (+/-) RNA viruses?

A

RNA-dependent RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What enzyme is needed for the transcription of SS (+) RNA viruses?

A

None, it acts directly as mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Does the mRNA have to be sense or anti-sense in-order for translation to occur?

A

(+) sense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What enzyme is required for viral DNA replication?

A

DNA-dependent DNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain how SS (+) RNA retroviruses are replicated?

A

SS (+) RNA > SS (-) DNA by RNA-dependent DNA polymerase > DS (+/-) DNA by DNA-dependent DNA polymerase > DS (+/-) > SS (+) RNA by DNA-dependent RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain how SS (-) RNA viruses are replicated?

A

SS (-) RNA > SS (+) RNA by RNA-dependent RNA polymerase > SS (+) RNA > SS(-) RNA by RNA-dependent RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain how DS (-/+) RNA viruses are replicated?

A

DS (-/+) RNA virus > DS (-/+) RNA virus by RNA-dependent RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a retrovirus?

A

A SS enveloped RNA virus that forms DNA from RNA using reverse transcriptase. It then incorporates its DNA into the host cell genome using an integrase enzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do naked viruses release from the host cell?

A

Released due to cell lysis - viral multiplication inhibits cell survival signals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do enveloped viruses release from the host cell?

A

The nucleocapsid merges with the plasma membrane > acquires an envelope from the plasma membrane > released by exocytosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What virus causes erythema infectiosum (slapped check virus)?

A

Parovirus B19.

17
Q

What are the signs & symptoms of erythema infectiosum?

A

Rash in children, may cause arthritis.

Dangerous in pregnancy & sickle cell.

18
Q

What virus causes roseola infection?

A

Herpes virus 6 & 7.

19
Q

What are the signs & symptoms of roseola infection

A

Flu-like symptoms & fever followed by a rash.

20
Q

What virus family causes molluscum contagiosum?

A

Poxviridae.

21
Q

What virus causes hand, foot & mouth in children?

A

Coxsachie virus.

22
Q

What virus causes croup?

A

Parainfluenza virus.