In Class Exam Style Questions

Question 1

E. coli polA mutants have a defective DNA polymerase that lacks
the 5’ to 3’ exonuclease activity. How will this affect replication?

a) The leading strand will not be extended by DNA polymerase I.
b) DNA polymerase I will not be able to excise the RNA primers
c) DNA polymerase I will be unable to catalyze the addition of
deoxyribonucleotides to RNA primers
d) DNA polymerase I will be unable to form a phosphodiester link
between adjacent Okazaki fragments
e) None of the above

Answer 1

b) DNA polymerase I will not be able to excise the RNA primers

Question 2

A fragment of partially double-stranded DNA has
the structure (5’denotes the 5’monophosphate; 3’denotes
the 3’ OH group)
AGTTATTA
3’-TCGATCAATAATGC-5’
If this DNA was used as a template for DNA polymerase III,
what nucleotide would be incorporated next?

a) A
b) T
c) C
d) G
e) U

Answer 2

c) C

Question 3

Okazaki fragments are associated with
synthesis of…
A. the leading strand.
B. the lagging strand.
C. both the leading and the lagging
strands.
D. single-stranded circular DNA.
E. RNA.

Answer 3

The lagging strand

Question 4

Which of the following does NOT employ bidirectional
replication to copy DNA?
A. theta replication
B. rolling-circle replication
C. linear replication
D. All of the above use bidirectional replication
E. None of the above use bidirectional replication

Answer 4

Rolling Circle Replication

Question 5

Primers are removed by
A. DNA ligase.
B. DNA polymerase I.
C. DNA polymerase III.
D. topoisomerase.
E. None of the above.

Answer 5

B. DNA polymerase I

Question 6

DNA replication is an incredibly accurate process. When a rare
mistake is made, most of the time a 3 ́→ 5 ́ exonuclease activity
will remove the mismatched nucleotide. In E. coli, this
proofreading activity is provided by
A. DNA polymerase I.
B. DNA polymerase III.
C. both DNA polymerase I and III.
D. DNA gyrase.
E. DNA ligase.

Answer 6

C. both DNA polymerase I and III.

Question 7

Eukaryotic DNA replication is similar to prokaryotic DNA
replication in many respects and similar proteins or protein
complexes are required. Which of the following is NOT a correct
functional matching of E. coli and eukaryotic replication
proteins?
A. primase; DNA polymerase α
B. DNA helicase; MCM complex
C. DNA polymerase III; DNA polymerase ε
D. DNA polymerase I; translesion DNA polymerase
E. All of the above are correct matchings.

Answer 7

D. DNA polymerase I; translesion DNA polymerase

Question 8

Replication of eukaryotic chromosomes presents several
challenges that are not found in prokaryotic cells. These
challenges include all of the following EXCEPT
A. eukaryotic DNA polymerases are, in general, much more
error-prone.
B. removal and reassembly of nucleosomes.
C. replication of chromosome ends.
D. coordination of replication with the cell cycle.
E. eukaryotic helicase binds double stranded DNA

Answer 8

A. eukaryotic DNA polymerases are, in general, much more
error-prone.