pre exam 2

Question 1

mutagens

Answer 1

physical or chemical agents that can cause mutations

Question 2

average mutation rate in humans

Answer 2

2.5 x 10^-8 mutations per nucleotide (175 mutations per diploid genome per generation)

Question 3

types of point mutations

Answer 3

base-pair substitutions - replaces one nucleotide and its partner with another pair of nucleotides

insertion or deletions - additions or losses of nucleotide pairs in a gene
*more severe effect!

Question 4

types of base-pair substitutions

Answer 4

silent mutations - no effect on amino acid because of redundancy in genetic code

missense mutations - still code for an amino acid, but not necessarily the right amino acid

nonsense mutations - change codon into stop codon, nearly always leading to a nonfunctional protein

Question 5

info on insertions/deletions

Answer 5

• can have a disastrous effect on protein
• may alter the reading frame, producing a frameshift mutation
• can occur during DNA replication, recombination, or repair

Question 6

what are the effects of DNA damage and mutations?

Answer 6

• developmental abnormalities
• senescence
• apoptosis
• tumors

Question 7

emergence of a variant in a population

Answer 7

• pop. initially dominated by one form of virus
• random variants exist at low levels or develop spontaneously
• variant gains competitive advantage due to natural selection (can coexist with initial form or become dominant)
• new variants can continue to emerge

Question 8

consequences of new gene variants

Answer 8

• variant may spread more quickly, cause more severe disease, and may be more deadly
• virus may evade diagnostic tests
• variants may be more resistant or immune to therapies
• may gain ability to escape recognition by immune system, making vaccines and natural immunity not effective