gene mutation quiz

somatic mutation

everything but germ cells, do NOT divide

transition

purine → purine, pyrimidine → pyrimidine

transversion

purine → pyrimidine, pyrimidine → purine

insertions and deletions lead to…

frameshift mutations

fragile-x chromosome

fragile site on the long arm due to expanding repeats

missense

amino acid becomes a different amino acid

nonsense

amino acid becomes a STOP codon

silent

codon becomes a synonymous codon

forward

wild type → mutant type

reverse

mutant type → wild type

suppressor

hides or suppresses the effect of another mutation

intragenic suppressor

first and second mutation happen in the same gene

intergenic suppressor

second mutation occurs in a different gene than the first

neutral

no changes in function

gain-of-function

a new function is developed from the mutation

loss-of-function

a function is lost from the mutation

conditional

mutation only occurs under certain conditions

lethal

mutation kills the organism

tautomeric shifts

tautomers(other forms of purines and pyrimidines) and wobble (nonstandard) base pairing leads to replication error; proofreading activity must miss it

strand slippage can cause

insertions and deletions

depurination

loss of purine from nucleotide (called an apurinic site), DNA polymerase usually adds an A which leads to permanent mutation

deamination

amino acid group is removed and alters DNA bases

what forms thymine dimers and increases mutation rates

UV and radiation

mismatch repair

mismatched bases and other DNA lesions are corrected

what happens during mismatch repair?

enzymes cut out a section of a new strand and replace with new nucleotides