Viral Evolution

Question 1

What is degeneracy

Answer 1

Redundancy of genetic code

Genetic code has redundancy but no ambiguity

Question 2

Silent mutations

Answer 2

When change in nucleotide results in same AA

Question 3

Missense mutations

Answer 3

When change in nucleotide results in different AA

Question 4

Nonsense mutations

Answer 4

When change in nucleotide codes for a STOP codon

Question 5

Insertions

Answer 5

Adding 1+ nucleotide

1-2 nucleotdies: shift in reading frame

3 nucleotides: same reading frame. Depending on where codon is, will either drastically affect protein or have little effect

Question 6

Deletions

Answer 6

Removing 1+ nucleotide

1-2 nucleotides: frame-shift

Question 7

T/F RNA viral polymerase lacks proofreading

Answer 7

True – RNA viruses mutate much faster than DNA viruses

Question 8

What is genomic drift

Answer 8

Cumulative point mutations due to lack of proof-reading

Question 9

What is genomic shift

Answer 9

Mutations due to copy choice mechanism (jumping of polymerase from one template to another = recombination) or reassortment (from other viruses)

Question 10

What is recombination

Answer 10

Polymerase jumping from one template to another by a copy choice mechanism – example of genomic shift

Question 11

What is reassortment

Answer 11

Occurs in segment genomes

Copying segments from different sources (ie a strain of flu that comes from pig, avian, and human)

Question 12

Quasispecies

Answer 12

In each host, viral clones will be slightly different

Affects vaccines – some vaccines wont wipe out all quasispecies and those that survive will promote resistance

Question 13

Explain difference between recombination and reassortment

Answer 13

Recombination = polymerase jumping from different templates (copy choice mechanism)

Reassortment = using segment from different soruces

Question 14

Which viruses can undergo reassortment?

Answer 14

Segmented RNA viruses

Reo-
Birna-
Bunya-
Arena-
Orthomyxo-