Nucleic Acids and the Genetic Material Problem Set

Problem 3 Tutorial: The replication fork

In this diagram of the process of DNA replication at a replication fork, the strand labeled B is the:

DNA Replication

  • The two antiparallel strands are replicated simultaneously in both directions.

  • RNA primers are used to initiate a new strand.

  • The parent strand at the 3' end of the template determines the daughter or leading strand in continuous replication.

  • The parent strand at the 5' end of the template produces the lagging strand as short pieces of DNA (100-200 nucleotides in eukaryotes and longer in prokaryotes).

  • The lagging strand fragments are called Okazaki fragments after their discoverer, Reiji Okazaki.

  • The RNA primers are removed by DNA polymerase and the fragments are joined by DNA ligase.

Direction of replication

New strands are always synthesized in the 5' to 3' direction. The 5' triphosphate can only be added to a free 3'OH of deoxyribose.

The replication fork

The Biology Project
University of Arizona
Thursday, October 3, 1996
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