DNA Replication

Which of the following unwind the double helix strand of DNA during DNA replication?

• DNA helicase

• Topoisomerase

• DNA Polymerase I

• DNA Polymerase III

In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of 14N?

• A

• B

• C

• D

A new DNA strand elongates only in the 5’ to 3’ direction because _____.

• DNA polymerase begins adding nucleotides at the 5’ end of the template

• The polarity of the DNA molecule prevents addition of nucleotides at the 3’ end

• Replication must progress toward the replication fork

• DNA polymerase can add nucleotides only to the free 3’ end

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5’ to 3’ direction?

• DNA polymerase III

• DNA polymerase I

• primase

• helicase

Which of the following is the enzyme that replaces the RNA nucleotides in a primer with DNA nucleotides?

• DNA polymerase III

• DNA polymerase I

• primase

• helicase

What is the function of topoisomerase?

• relieving strain in the DNA ahead of the replication fork

• elongating new DNA at a replication fork by adding nucleotides to the existing chain

• unwinding of the double helix

• stabilizing single-stranded DNA at the replication fork

The enzyme that carry out the above function is

• Primase

• Topoisomerase

• DNA Polymerase I

• DNA Polymerase III

Which of the following Add free DNA nucleotides to the RNA primer or pre-existing DNA strand complementary to the bases of the template?

• DNA helicase

• Topoisomerase

• DNA Polymerase I

• DNA Polymerase III

DNA is synthesized through a process known as _____.

• semiconservative replication

• conservative replication

• translation

• transcription

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

• It synthesises RNA nucleotides to make a primer

• It joins Okazaki fragments together

• It unwinds the parental double helix

• It stabilizes the unwound parental DNA