Nucleic Acids and the Genetic Material Problem Set 1

Problem 5: More on the replication fork

In this diagram of the process of DNA replication at a replication fork, the black boxes labeled D and E are:

DNA Replication

  • DNA template with synthesis of a new strand in the 5' to 3' direction.

  • The 5' triphosphate can only be added to a free 3'OH of deoxyribose.

  • 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

The replication fork

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Thursday, October 3, 1996
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