DNA Structure and Replication · USMLE Step 1

Which statement correctly describes how replication forks proceed on circular prokaryotic chromosomes?

  1. Replication proceeds unidirectionally from a single origin
  2. Replication begins at multiple origins spaced around the chromosome
  3. Replication proceeds bidirectionally from a single origin
  4. Replication uses telomerase to replicate ends
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Correct answer: Replication proceeds bidirectionally from a single origin

In prokaryotes, replication starts at a single origin of replication and proceeds bidirectionally, creating two replication forks that copy the circular chromosome until completion.

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