Ch. 18 Gene Mutation and DNA Repair

Question 1

mutation

Answer 1

any inherited change in the genome (descendants may be cells or organisms)

Question 2

causes of mutations

Answer 2

1. errors during recombination
2. spontaneous errors during DNA replication (not as common)
3. exposure to mutagens, x rays, cosmic rays
4. spontaneous chemical changes in DNA bases

Question 3

mutations are ____ events

Answer 3

random

*mutations are unrelated to any adaptive advantage, they do not happen in order to be more or less fit, they just happen randomly. fitness and non-fitness happen after the fact as a result of the mutation

Question 4

germ line mutations

Answer 4

inherited (occurs in reproductive cells)

• meiosis and sexual reproduction pass germ line mutations to about 50% of offspring
• all offspring’s cells carry mutation

Question 5

somatic mutations

Answer 5

not inherited (occurs in non-reproductive cells)

Question 6

mutations are a ____ in a population and at the heart of ______

Answer 6

source of variation

evolution

Question 7

transition

Answer 7

change single nucleotide from a pyrimidine –> pyrimidine or a purine –> purine

Question 8

transversion

Answer 8

change single nucleotide from a pyrimidine –> purine or vice versa

Question 9

protein level mutations

Answer 9

missense
nonsense
silent

Question 10

effects of 5’ flanking region mutation

Answer 10

• regulatory mutation
• may effect initiation of transcription
• may affect RNA polymerase binding to promoter
• may affect enhancer regulation of transcription

Question 11

effects of exon mutations (UTR’s and ORF’s)

Answer 11

• coding mutation

- silent, missense, nonsense, frameshift

Question 12

effects of intron mutations

Answer 12

• noncoding mutation
• likely has no effect
• may effect enhancer regulation of transcription

Question 13

effects of intron/exon junction mutations

Answer 13

• splice site mutation

- may effect splicing of introns (incorrect splicing)

Question 14

effects of 3’ flanking region mutation

Answer 14

• regulatory mutation
• effects on termination
• effects on enhancer regulation of transcription

Question 15

protooncogene

Answer 15

gene with the potential to cause cancer
DOMINANT only need one copy to be functional
one mutated copy –> oncogene

Question 16

oncogene

Answer 16

gene that causes cancer

Question 17

tumor suppressor gene

Answer 17

only need one copy to be functional

if both copies fail, then you may get cancer