Deck 9: DNA Replication

Question 1

Which enzyme seals nicks and joins Okazaki fragments?
a.DNA polymerase I
b.DNA gyrase
c.DNA primase
d.DNA ligase
e.DNA helicase

Answer 1

DNA ligase

Question 2

Mismatch repair requires the ability to distinguish between template and newly synthesized DNA strands.How can E.coli distinguish between these two strands?
a.Template DNA is methylated.
b.New DNA is methylated.
c.Template DNA is phosphorylated.
d.New DNA is phosphorylated.
e.New DNA contains single-stranded binding proteins.

Answer 2

Template DNA is methylated.

Question 3

Okazaki fragments are found associated with
a.the leading strand.
b.the lagging strand.
c.both the leading and the lagging strands.
d.the base of the replication fork.

Answer 3

the lagging strand.

Question 4

You identify a mutant whose chromosomes shorten after each round of replication.A mutation in which gene would explain this observation?
a.DNA polymerase
b.telomerase
c.DNA ligase
d.DNA gyrase

Question 5

DNA polymerase requires a 3' OH group provided by a primer before it can begin DNA synthesis.How is it that the primer can be synthesized on the DNA without a 3' OH group?
a.The primer is RNA-synthesized by RNA polymerase,which does not require a 3' OH group.
b.These primers require an even shorter primer sequence.
c.The primer uses an artificial 3' OH group provided by a unique enzyme.
d. Primers use a 5' OH group.

Question 6

During replication,what is the role of helicase?
a.It joins Okazaki fragments on the lagging strand.
b.It stabilizes the single-stranded DNA.
c.It reduces torsional strain by making double-stranded DNA breaks.
d.It replicates the DNA.
e.It breaks hydrogen bonds between the two DNA strands.

Question 7

Eukaryotic DNA replication is similar to prokaryotic DNA replication.However,eukaryotes require unique replication strategies because of unique features of eukaryotic DNA.Which is NOT a unique feature linked to replication strategies?
a.Eukaryotic chromosomes are linear.
b.Eukaryotic chromosomes contain histone proteins.
c.Eukaryotic DNA contains introns.
d.Because of its size,eukaryotic DNA requires several replication forks.