Intro to Virus

Question 1

What are the 3 typical components of a virion?

Answer 1

1- Nucleic acid (DNA or RNA) Always
2-Protein sheath (Always)
3-Lipid envelope (sometimes)

Question 2

What are the 3 main shapes of a Viral capsid?

Answer 2

1-Icosahedral (spherical)
2-Helical (cylindrical)
3-Complex (Combination of icosahedral and cylindrical)

Question 3

What are the three basic functions of the capsid?

Answer 3

1-Protect genetic material
2-Aid in attachment to cell
3-package viral enzymes

Question 4

Icosahedral viruses are composed of __________ which are made up of 5-6 __________

Answer 4

capsomeres, protomers

Question 5

A viral protein layer found between the capsid and the envelope is called?

Answer 5

Tegument or matrix protein

Question 6

What are the 3 forms viral genetic information is found?

Answer 6

1-positive sense
2-negative sense
3-double stranded/ambisense

Question 7

What are the 7 groups of viruses according to the baltimore system?

Answer 7

1-DNA (+)
2-DNA (+/-)
3-DNA (+/-) RT
4-RNA (+)
5-RNA (-)
6-RNA (+/-)
7-RNA (+) RT

Question 8

The period in which the viral genetic information is “off the radar” and inside the cell is called?

Answer 8

Eclipse phase

Question 9

What are the two kinds of enveloped penetration?

Answer 9

1-Direct fusion (only capsid enters the cell, envelope becomes part of membrane)
2-Viropexis (receptor mediated endocytosis, capside and membrane are brought inside)

Question 10

Instead of being on the envelope surface, cell surface receptors interact directly with what in naked capsid penetration?

Answer 10

The spikes on the capsid

Question 11

Regardless of the type of genetic material, a virus must convert into which form in order to ultimately undergo viral replication and transcription?

Answer 11

mRNA

Question 12

Which type of virus uses host transcription processes to produce mRNA from its template?

Answer 12

DNA virus

Question 13

A series of viral genomes is called what?

Answer 13

Concatemer

Question 14

What two phases might a DNA virus have?

Answer 14

1-Latent phase- dormant

2-Lytic phase- replicating

Question 15

Sequential phase expression of a viral genome is known as?

Answer 15

complex expression (each set of proteins help set up the next set)

Question 16

Which type of virus is directly translated in the cell?

Answer 16

RNA (+) viruses (RNA (-) strand is also made for replication purposes)

Question 17

Which type of virus brings it’s own reverse RNA polymerase to convert its anti sense strand into readable form?

Answer 17

RNA (-)

Question 18

The use of reverse transcriptase to convert RNA to DNA and integrate into host genome is typical of which virus type?

Answer 18

Retrovirus

Question 19

Once integrated into the genome and replicated the retrovirus is said to be a what?

Answer 19

provirus

Question 20

Capsid formation, “Encapsidation” favors the incorporation of?

Answer 20

the viral genome

Question 21

what part of a virus does the human immune system respond to and recognize as foreign?

Answer 21

the envelope proteins or spikes

Question 22

T/F: Naked and enveloped viruses can both use viropexis to enter the cell?

Answer 22

true