Final answer:
The unwinding of the double helix during theta replication generates a loop known as a replication fork. This is part of the process where enzymes like helicase and topoisomerases help in unwinding DNA to form new strands in a semi-conservative manner.
Step-by-step explanation:
The unwinding of the double helix during theta replication generates a loop, termed a replication fork. This process involves the enzyme helicase unwinding the DNA, and topoisomerases relieving the stress of unwinding, leading to the formation of replication forks at each replication origin as the DNA unwinds further. DNA replication is semi-conservative, meaning the new DNA molecule consists of one old and one new strand.
During the initiation in E. coli, for example, after breaking hydrogen bonds at the origin of replication, the DNA double helix progressively unzips, leading to the formation of a replication bubble. The newly exposed single strands of DNA serve as templates for new DNA synthesis, where DNA polymerase III plays a crucial role in elongating new DNA.