Q163 / 180 · NEET 2017 · Zoology
During DNA replication, Okazaki fragments are used to elongate:
- AThe leading strand towards replication fork
- BThe lagging strand towards replication fork
- CThe leading strand away from replication fork
- Correct answerDThe lagging strand away from the replication fork
Solution
The DNA polymerase III molecule helps in the DNA fork to synthesize simultaneously the DNA. One of the strands, with proper orientation, functions as a leading strand for which the synthesis is continuous. The lagging strand is oppositely oriented and thus, DNA Pol-III synthesizes this in fragments called the Okazaki fragment. Each Okazaki fragment is synthesized by DNA polymerase at lagging strand in direction. New Okazaki fragments appear as the replication fork opens further.
As the first Okazaki fragment appears away from the replication fork, the direction of elongation would be away from replication fork.
As the first Okazaki fragment appears away from the replication fork, the direction of elongation would be away from replication fork.
Hence, the correct answer is option: 'D'.