• Created by: 03Louise
  • Created on: 17-01-19 16:11

DNA replication

  • 1.       Helicase unwinds and separates the parental strand
  • 2.       Another enzyme relieves the strain created by cutting the DNA creating a temporary break
  • 3.       Free DNA mononucleotides join onto both strands by complementary base pairing, DNA polymerase adds these to the strand.
  • 4.       DNA ligase joins the mononucleotides by creating phosphodiester bonds between them
  • 5.       On one strand this is constant and the other creates okazaki fragments which are later joined together

Proof of DNA semi-conservative replication

  • Bacteria grown in heavy 15N
  • Some bacteria are transferred into light 14N and bacteria continue to grow
  • A sample is taken after 20 minutes after one replication and 40 minutes after two replications
  • Samples of extracted DNA is placed in test tubes
  • The first accumulated at the bottom, the second in the middle and the third in the


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