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Processes of DNA

10th Grade

Biology

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DNA Replication

  • The process of making a copy of DNA is DNA Replication
  • This process occurs in INTERPHASE of the cell cycle
  • The first stage of DNA replication is the separation of the strands.

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DNA Helicases

  • The double helix unwinds by enzymes called DNA helicases.
  • Helicases break the hydrogen bonds that link the nitrogen bases .

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DNA Polymerase

  • After the strand separates, DNA polymerase move along each DNA strand.
  • DNA Polymerase adds nucleotides to the exposed nitrogenous bases.
  • As DNA polymerases move along, two new double helixes are formed.

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Final Step

  • Once the DNA polymerase has finished copying the DNA strand, two new strands which are identical are created.

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Links:

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Errors

  • During DNA replication, errors can sometimes occur, and the wrong nucleotide is added to the new strand.
  • DNA polymerase III also goes along the strand and “proofreads” the strand and corrects any errors. This reduces the number of errors to about 1 error per 1 billion nucleotides

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Rate of Replication

  • The DNA strand has an estimated 3.1 billion base pairs (A,C,T,G).
  • The DNA strand is not replicated from start to finish.
  • Rather, it is divided into 100 sequences about 100,000 bases and DNA replication begins