Question

On the lagging strand of a replicating DNA, one would expect to find

a) no Okazaki fragments
b) Okazaki fragments, RNA primer and DNA polymerase
c) only Okazaki fragments.
d) only DNA polymerase and Okazaki fragments

Answer 1

The presence of Okazaki fragments, RNA primer, and DNA polymerase is expected on the lagging strand of a replicating DNA. The lagging strand synthesis is discontinuous, opposing the replication fork's direction, relying on RNA primers and DNA polymerase to add nucleotides and forming Okazaki fragments, which are later joined by ligase.

Step-by-step explanation:

Okazaki fragments are short lengths of DNA found on the lagging strand during DNA replication. They are synthesized in a direction away from the replication fork, due to the antiparallel nature of the DNA double helix, and the requirement for DNA polymerase to operate in the 5' to 3' direction. Hence, while one strand, called the leading strand, is synthesized continuously in the direction of the replication fork, the other strand, called the lagging strand, is synthesized discontinuously. Each Okazaki fragment begins with an RNA primer laid down by the enzyme primase, which provides a starting point for DNA polymerase to add DNA nucleotides.

Afterward, DNA polymerase I replaces the RNA primer with DNA nucleotides. DNA ligase then joins the Okazaki fragments together, creating a continuous strand of DNA.