Question

In bacteria, the DNA polymerase on the leading strand template ______?

1) stays tethered to a single B clamp during replication
2) switches from B clamp to B clamp
3) does not need a B clamp
4) stays bound to an a clamp

Answer 1

In bacteria, during DNA replication, the DNA polymerase on the leading strand 1) stays tethered to a single B clamp (sliding clamp) to allow continuous synthesis in a 5' to 3' direction, supported by proteins such as topoisomerase and DNA ligase for successful DNA strand formation. Hence, 1) is correct.

Step-by-step explanation:

In bacteria, the DNA polymerase on the leading strand template stays tethered to a single B clamp during replication. This is because, in contrast to the lagging strand, the leading strand is synthesized continuously.

The sliding clamp, often referred to as the B clamp in bacteria, is a ring-shaped protein that securely binds to the DNA, allowing the polymerase to stay in place and efficiently add nucleotides in a 5' to 3' direction as it moves forward. Topoisomerase helps by preventing the overwinding of the DNA ahead of the replication fork.

Finally, after the RNA primers are removed and the gaps filled by DNA nucleotides, DNA ligase seals the nicks, completing DNA synthesis and ensuring the stability of the new DNA strand.