Genetics and Replication

Question 1

T/F - Viruses have greater genetic diversity than any other group of organisms.

Answer 1

True

Question 2

How is a virus’ genome diversified?

Answer 2

1. Mutation
2. Recombination
3. Reassortment

Question 3

What is a mutation?

Answer 3

Single nucleotide change within a single genome. This occurs during replication and changes the genotype (can but doesn’t necessarily change the phenotype).

Question 4

Does recombination and reassortment exchange nucleotide sequences within a single genome or between one genome and another?

Answer 4

Between one genome and another

Question 5

Why do you think DNA viruses mutate at essentially the same rate as our own cells?

Answer 5

Because viruses are using the same machinery as our cells.

Question 6

T/F - RNA viruses are less likely to have mutations.

Answer 6

False - RNA virus mutations occur 1/1000 bps and DNA virus mutations occur 1/1 Bill bps.

Question 7

Viral RNA polymerases have NO ____________ mechanisms.

Answer 7

Proofreading - this means that when there is a mutation or incorrect bp, there is no way to check for it and change it.

Question 8

T/F - RNA viruses are very error prone.

Answer 8

True

Question 9

Do all RNA viruses, minus retroviruses, encode a RNA-dependent RNA polymerase (no proofreading)?

Answer 9

Yes

Question 10

Retroviruses encode a RNA-dependent ___ polymerase which has low fidelity (very error prone).

Answer 10

DNA polymerase

Question 11

What is a substitution or point mutation?

Answer 11

One nucleotide change

Question 12

What is an inversion?

Answer 12

Adjacent nucleotides change position

Question 13

What is an insertion or deletion and what occurs when this happens?

Answer 13

One or more nucleotide are added or removed. This causes a change in the reading frame (usually 3 codons - if one is added or removed it changes the frame)

Question 14

What is a silent mutation?

Answer 14

Change in the bp but it doesn’t change the translated amino acid. It usually occurs at the 3rd position.

Question 15

What is a missense mutation?

Answer 15

Mutation causes a change in amino acid

Question 16

What is a nonsense mutation?

Answer 16

Introduces a stop codon, either at the site of the mutation, or downstream if the reading frame is altered by the mutation.

Question 17

T/F - An amino acid is coded for by 3 nucleotides, so changing the groupings of 3 nucleotides changes the codons and can therefore change the amino acids.

Answer 17

True