What is the replication fork?

What is the replication fork?

• A. A Y-shaped point where the two strands separate
• B. A protein that unzips DNA
• C. A site where transcription occurs
• D. The end of a chromosome

Answer: (A)

The replication fork is the Y-shaped region where the two strands of the DNA double helix are unwound and separated so that new DNA strands can be synthesized. This unzipping is carried out by helicase, and the fork forms at the origins of replication, creating a template for copying. As the fork opens, single-stranded binding proteins stabilize the exposed strands, and topoisomerase relieves twisting ahead of the fork. DNA polymerases then build the new DNA: the leading strand is made continuously toward the fork, while the lagging strand is made in short fragments (Okazaki fragments) that are later joined. This structure is distinct from a single protein that unzips DNA, a site of transcription, or the end of a chromosome (telomere).

The replication fork is the Y-shaped region where the two strands of the DNA double helix are unwound and separated so that new DNA strands can be synthesized. This unzipping is carried out by helicase, and the fork forms at the origins of replication, creating a template for copying. As the fork opens, single-stranded binding proteins stabilize the exposed strands, and topoisomerase relieves twisting ahead of the fork. DNA polymerases then build the new DNA: the leading strand is made continuously toward the fork, while the lagging strand is made in short fragments (Okazaki fragments) that are later joined. This structure is distinct from a single protein that unzips DNA, a site of transcription, or the end of a chromosome (telomere).