Module 15: DNA Replication Flashcards

Flashcards covering DNA replication enzymes, repair mechanisms, directional synthesis, and replication fork diagrams.

What is the function of Topoisomerase in DNA replication?

Prevents DNA supercoiling and breakage

What is the function of Helicase in DNA replication?

Unwinds DNA starting at the origin of replication

What is the function of Primase in DNA replication?

Lays complementary RNA nucleotides and acts as a starting point

What is the function of DNA Polymerase III during replication?

Lays DNA nucleotides

What is the function of DNA Polymerase I during replication?

Replaces RNA nucleotides with DNA

What is the function of Ligase during DNA replication?

Joins Okazaki fragments together

How is Proofreading defined in the context of DNA repair?

DNA Polymerase III catches own mistakes and replaces nucleotides

How are Mismatch Repairs defined in the context of DNA repair?

DNA is scanned for incorrect nucleotides after replication

How is Nucleotide Excision Repair defined in the context of DNA repair?

Segment of DNA is removed and replaced with correctly paired nucleotides

In what direction is DNA synthesized?

DNA is synthesized $5'$ to $3'$

Why is DNA synthesized in the $5'$ to $3'$ direction?

Because DNA polymerase adds nucleotides only to a free $3'\text{ OH}$

Why is there a leading and a lagging strand in DNA replication?

Because the templates are antiparallel, the leading strand is made continuously toward the fork; the lagging strand is made away from the fork in Okazaki fragments

According to this color-coded DNA replication diagram, which enzyme is represented by the green rectangle that adds RNA nucleotides?

Primase

What structure of replicating DNA is illustrated in this diagram showing RNA primers on synthesized strands?

A replication bubble containing synthesized leading and lagging strands

In this labeled replication bubble diagram, in which direction is the leading strand synthesized relative to the replication fork?

Continuously toward the replication fork

Which enzyme replaces RNA nucleotides with DNA nucleotides on the newly synthesized strand?

DNA Polymerase I

Which enzyme unwinds the DNA helix starting at the origin of replication?

Helicase

Which enzyme connects separate Okazaki fragments together on the lagging strand?

Ligase

Which type of DNA repair occurs after replication by scanning the DNA for incorrect nucleotides?

Mismatch Repairs

What are the short segments of DNA synthesized away from the replication fork on the lagging strand called?

Okazaki fragments