With reference to the mechanisms of mismatch repair and
nucleotide-excision repair in E.
coli cell, which mechanism is more energy costing?
Explain your answer.
Match each DNA repair mechanism with its description.
photoactive repair
base excision repair
nucleotide excision repair
mismatch repair
SOS system
nonhomologous end-joining
A.
recognizes newly synthesized but improperly paired DNA and nicks
the strand to replace
B.
cuts a piece out of distorted DNA to be filled in by
polymerase
C.
an emergency, error-prone effort to salvage replication of
damaged DNA
D.
removes and replaces depurinated or deaminated bases from
sugars
E.
repairs pyrimidine dimers in the presence of light...
Compare and contrast the processes of base excision repair and
methyl-directed mismatch repair in prokaryotes. In your answer
discuss:
a) Under which circumstances this mechanism will need to be used
in the cell.
b) The sequence of events that occur in the repair process.
c) The names and roles of the enzymes involved in each repair
mechanism.
In the mismatch repair system, the MutS protein initiates the
repair process, and the MutHL excision complex acts by cutting
A)
The methylated strand of the double helix
B)
Any U:A base pairs found in the DNA
C)
Any G:T base pair
D)
The non-methylated strand of the double helix
E)
The site of the helix distortion
What are the differences between Holliday model recombination
and double-stranded break repair recombination? What experiments
can be conducted to determine which is taking place?
Describe the mechanism underlying the below repair
mechanisms.
a. Mismatch Repair
b. Postreplication Repair
c. SOS Repair
d. Photoreactivation Repair
e. Base Excision Repair
f. Nucleotide Excision Repair
g. Doublestranded Break Repair
During mismatch repair, how does the cell “know” which strand to
degrade and repair? Why will it lose this ability after a certain
amount of time? Provide a reason that might explain why it is safer
to degrade the new strand of DNA rather than the parental
strand.
A double stranded DNA molecule was found to have a total of
10,000 A+T base residues and 14,000 G+C residues. Analysis of one
of the strands of DNA showed that it had 3,000 A and 4,000 C
residues. What is the number of T and G base residues on this
strand?