The enzyme DNA polymerase works only in the 5′ to 3′ direction. How does this affect the leading strand and the lagging strand?

Question

Question 13 options:

A)

DNA polymerase can work on both the leading and the lagging strand but is much faster on the leading strand.

B)

DNA polymerase can use only the leading strand as a template. A different enzyme is used to synthesize DNA on the lagging strand.

C)

DNA polymerase can work continuously on the leading strand but works discontinuously on the lagging strand, creating Okazaki fragments.

D)

DNA polymerase can work continuously on the leading strand but must flip the lagging strand around before it can work on it.

Answer 1

The correct answer is:

C) DNA polymerase can work continuously on the leading strand but works discontinuously on the lagging strand, creating Okazaki fragments.

Explanation: DNA polymerase synthesizes new DNA strands in the 5′ to 3′ direction. On the leading strand, which is oriented in the 3′ to 5′ direction relative to the replication fork, DNA polymerase can synthesize continuously as the fork opens. In contrast, the lagging strand is oriented in the opposite direction (5′ to 3′ relative to the fork) and is synthesized discontinuously in short segments called Okazaki fragments. These fragments are later joined together by the enzyme DNA ligase.