DNA Replication

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

• RNA primase
• single–strand binding proteins
• DNA polymerase I
• DNA ligase

What is meant that DNA replication follows a “semi-conservative” model?

• After DNA replication, each DNA molecule contains one original strand and one new strand

• After DNA replication, one DNA molecule contains two original strands while the other contains two new strands

• None of these identify the “semi-conservative” model.
• After DNA replication, each DNA molecule contains a mixture of both original and new DNA dispersed throughout each strand.

This enzyme helps helicase unzip DNA by relieving supercoiling

• Topoisomerase

• Exonuclease

• DNA Primase

• DNA Polymerase

Okazaki fragments are found on the _______________ strand

• Leading

• Lagging

DNA is built in this direction

• 5^' to 3' (new nucleotides added to the 3' end)

• 3' to 5' (new nucleotides added to the 5' end)

• 3' to 5' (new nucleotides added to the 3' end)

• 5^' to 3' (new nucleotides added to the 5' end)

DNA Replication occurs during which phase of the cell cycle?

• G ₁ phase

• S phase

• G ₂ phase

• Mitotic phase

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

• DNA polymerase can join new nucleotides to the 3' end of the preexisting strand.
• Helicases and single-strand binding proteins work at the 5' end.
• The origins of replication occur only at the 5' end.
• DNA ligase works only in the 3' to 5' direction

How does helicase create the replication fork (ie. separate the strands of DNA).

• By using a primer

• By using DNA polymerase

• By breaking the hydrogen bonds between base pairs

• By breaking the covalent bonds between base pairs

How do the leading and the lagging strands differ?

• The leading strand is synthesized into the replication fork, and the lagging strand is synthesized in the opposite direction.

• The leading strand is synthesized at twice the rate of the lagging strand.

• The leading strand is synthesized in short fragments that are ultimately stitched together, whereas the lagging strand is synthesized continuously.

• The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

The primer is composed of _____.

• amino acids

• RNA only

• DNA only

• RNA and DNA