DNA Replication

Summary on DNA replication, together with its importance and structure of DNA.

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  • Created by: Medha
  • Created on: 30-06-09 15:25

DNA - Deoxyriobose Nucleic Acid

DNA - is a polymer of nucleotide.

Nucleotide - is a complex molecule consisting of 3 molecules linked together ie pentose sugar, phosphate group and nitrogenous base.

Structure of DNA:

  • It's a polynucleotide.
  • DNA later coils into helical shapes, this provides stability.
  • Exsists as a double helix structure.
  • These 2 chains run anti-parallel to each other. (one is 5' end to 3' end, the other is 3' end to 5' end)
  • It's highly stable, to maintain the genetic information unchanged throughout life.
  • The stability is maintained by the Hydrogen bonds

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Importance of DNA Replication

  • Inheritance of genes from parents to offsprings.
  • Help in growth and repair.
  • Avoid mutations.

DNA Replication - ability of a DNA to be perfectly copied as many times over, so as to maintain the same genetic material.

DNA replication is a semi-conservative replication.

Semi-conservative replication - method bywhich a DNA molecule is copied toform two identical molecules, each containing one strand from the original molecule and one newly synthesised strand.

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  • The two strands unzip and unwind due to the breaking of Hydrogen bonds in the presence of Helicase enzyme.

  • The strand acts as a template, where by free nucleotides with complementary base, pair to those exposed on the template. (Free nucleotides are activated by an extra phospahte attaching to them)

  • The nucloetides join to each other by the formation of Hydrogen bonds, catalysed by the enzyme DNA Polymerase.

  • The short segments formed along the new strand (the lagging strand) are joined in the presence of the enzyme Ligase.

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