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:
- 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
- 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
University of Arizona
Thursday, October 3, 1996
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