Question

Describe the events that occur at an origin of replication during initiation of replication in E. coli.

A. DNA helicase unwinds the DNA double helix, and DNA polymerase synthesizes the RNA primer.
B. The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments.
C. Primase synthesizes RNA primers, and DNA polymerase III elongates the leading strand.
D. DNA ligase joins Okazaki fragments on the lagging strand.

Answer 1

During the initiation of replication in E. coli, DNA helicase unwinds the DNA double helix, primase synthesizes RNA primers, DNA polymerase III elongates the leading strand, and DNA ligase joins Okazaki fragments on the lagging strand.

Step-by-step explanation:

Events at the Origin of Replication during Initiation of Replication in E. coli

1. DNA helicase uses the energy from ATP hydrolysis to separate the DNA strands, forming replication forks.
2. Primase synthesizes RNA primers, which DNA polymerase III uses as a starting point for DNA synthesis.
3. The leading strand is synthesized continuously by DNA polymerase III, while the lagging strand is synthesized in short Okazaki fragments.
4. RNA primers are removed and replaced with DNA nucleotides by enzymes such as DNA polymerase I.
5. DNA ligase joins the Okazaki fragments on the lagging strand by forming phosphodiester bonds.