Question

What is the characteristic of DNA synthesis that is semidiscontinuous, involving the leading and lagging strands?

A) The leading strand is synthesized discontinuously, while the lagging strand is synthesized continuously.
B) Both the leading and lagging strands are synthesized continuously.
C) The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously.
D) Both the leading and lagging strands are synthesized discontinuously.

Answer 1

DNA synthesis is semidiscontinuous with the leading strand synthesized continuously in the 5’-3’ direction, and the lagging strand synthesized discontinuously in short Okazaki fragments.

Step-by-step explanation:

The characteristic of DNA synthesis that is semidiscontinuous involves a continuous synthesis on the leading strand and a discontinuous synthesis on the lagging strand. The enzyme DNA polymerase can only add nucleotides to the free 3' end, meaning synthesis can only proceed in the 5'-3' direction. Therefore, the leading strand is synthesized in one continuous piece as the replication fork moves forward. In contrast, the lagging strand, which runs in the opposite direction to the replication fork, is synthesized in short segments known as Okazaki fragments which are subsequently joined together to form a continuous strand. This semidiscontinuous replication ensures both strands are synthesized concurrently despite the antiparallel orientation of the DNA strands.