Chapter 7 HW Flashcards
forward mutations
change a wild-type allele to a different allele
a change from an A ti a C in DNA sequence is a
transversion
missense mutations
change the amino acid sequence of a polypeptide
frameshift mutations
- are caused by insertions or deletions within the reading frame of a gene
- often caused a truncated gene product
chromosomes can undergo
inversions, deletions, translocations
spontaneous mutations
happens during the normal operation of the cell
spontaneous mutations rates vary
- from gene to gene
- from species to species
mutations arise
spontaneously before exposure to a selective agent
cytosine spontaneously deaminates to form
uracil
UV light
forms thymine dimers
complementation testing
- reveals whether two mutations are in the same gene
- was used to define complementation groups
Benzer used
- intragenic recombination
- worked with phages
fine structure mapping of phage T4
showed that some nucleotides were more susceptible to mutations than others
Beadle and Tatum
developed the “one gene, one enzyme” hypothesis
auxotrophs
are mutant strains that can’t grow on minimal media
mismatch repair
catches mistakes that proofreading misses
the dam methylase
methylates adenines at the sequence GATC
photoreactivation
is an example of repair by direct reversal
glycosylases
breaks the bond holding the base to a sugar
nucleotide excision repair
doesn’t recognize a particular lesion but distortions in the double helix
