Chapter 7 HW

Question 1

forward mutations

Answer 1

change a wild-type allele to a different allele

Question 2

a change from an A ti a C in DNA sequence is a

Answer 2

transversion

Question 3

missense mutations

Answer 3

change the amino acid sequence of a polypeptide

Question 4

frameshift mutations

Answer 4

• are caused by insertions or deletions within the reading frame of a gene
• often caused a truncated gene product

Question 5

chromosomes can undergo

Answer 5

inversions, deletions, translocations

Question 6

spontaneous mutations

Answer 6

happens during the normal operation of the cell

Question 7

spontaneous mutations rates vary

Answer 7

• from gene to gene
• from species to species

Question 8

mutations arise

Answer 8

spontaneously before exposure to a selective agent

Question 9

cytosine spontaneously deaminates to form

Answer 9

uracil

Question 10

UV light

Answer 10

forms thymine dimers

Question 11

complementation testing

Answer 11

• reveals whether two mutations are in the same gene
• was used to define complementation groups

Question 12

Benzer used

Answer 12

• intragenic recombination
• worked with phages

Question 13

fine structure mapping of phage T4

Answer 13

showed that some nucleotides were more susceptible to mutations than others

Question 14

Beadle and Tatum

Answer 14

developed the “one gene, one enzyme” hypothesis

Question 15

auxotrophs

Answer 15

are mutant strains that can’t grow on minimal media

Question 16

mismatch repair

Answer 16

catches mistakes that proofreading misses

Question 17

the dam methylase

Answer 17

methylates adenines at the sequence GATC

Question 18

photoreactivation

Answer 18

is an example of repair by direct reversal

Question 19

glycosylases

Answer 19

breaks the bond holding the base to a sugar

Question 20

nucleotide excision repair

Answer 20

doesn’t recognize a particular lesion but distortions in the double helix