40) Methyl methanesulfonate is an alkylating agent that adds bulky lesions to DNA and requires translesion synthesis by PolV (umuC/D’) for repair. Your labmate mixed up three strains of bacteria for a

40) Methyl methanesulfonate is an alkylating agent that adds bulky lesions to DNA and requires translesion synthesis by PolV (umuC/D’) for repair. Your labmate mixed up three strains of bacteria for a crucial experiment. These are:

X - umuC-

Y - wildtype

Z - ruvC-

You come up with a way to identify these strains. You plate out aliqouts of each onto media containing MMS. You observe the following results.

A) Which strain or strains will behave as shown on the light curve?  

a) Y

b) Y and Z

c) None

d) X and Y

e) Z

f) X

g) Y and X

B) Which strain or strains will behave as shown on the dark curve?  

a) Y

b) Y and Z

c) None

d) X and Y

e) Z

f) X

g) Y and X

C) If there are two strains that behave the same way, what other assay could you use to determine which strain has which genotype?  

a) Repeat using UV sensitivity – one mutant is likely to be more sensitive

b) Perform an Ames test – one mutant likely has higher mutation rates

c) None of these

d) Co-infect with phage and perform a cis test – one mutant will give lower recombination frequencies

e) Repeat using a higher MMS dose – one mutant is likely sensitive at a higher dose