Question

During dna replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as okazaki fragments. why is this so?

a) DNA polymerase can only synthesize in the 3' to 5' direction.
b) The two strands of DNA have opposite orientations.
c) DNA polymerase requires a primer to initiate synthesis.
d) The replication fork only allows synthesis in one direction.

Answer 1

During DNA replication, the leading strand is synthesized continuously because the DNA polymerase enzyme adds nucleotides in the 5' to 3' direction and follows the replication fork.

Step-by-step explanation:

The synthesis of the leading strand and the lagging strand during DNA replication involves different processes due to the anti-parallel nature of the two strands of DNA. DNA polymerase, the enzyme that synthesizes the new DNA strands, can only add nucleotides in the 5' to 3' direction. For the leading strand, this means synthesis is continuous and in the direction of the replication fork.

Conversely, for the lagging strand, DNA is synthesized in short segments, known as Okazaki fragments, because this strand runs in the opposite 3' to 5' direction relative to the replication fork, and thus has to be synthesized in a discontinuous manner away from the replication fork. The replication fork allows synthesis in both directions.