DNA replication


Transfer of genetic information

a) inheritance (via copied DNA) replication

b) expression (via mRNA) transcription

DNA replication

  • DNA, the genetic material of the cell, needs to be replicated every time the cell divides
  • during mitosis and meiosis, cells divide to form two daughter cells and the DNA needs to be replicated
  • DNA replication is the process of copying a parental DNA molecule to form two daughter DNA molecules

DNA replication is semi-conservative

  • double stranded DNA is unwound by helicase
  • each strand of the original double stranded DNA serves as a template for a new strand
  • an exact copy of the parent molecule is made
  • the new strands are called daughters strands
  • a parental strand is present in both daughter strands

What is need for DNA replication

  • the double helix needs to be unwound and separated to provide a template for copying
  • the polymerase needs a primer to start copying the DNA
  • dNTPS are needed to elongate the new strand
  • to replicate double stranded DNA by a DNA polymerase, many proteins and enzymes are required which act in a coordinated and cooperative manner
  • polymerase requires complementary nucleotides and primers

Components needed for replicating DNA

  • DNA helicase
  • SSBs
  • topoisomerases
  • primase
  • DNA polymerase
  • sliding DNA clamps
  • RNAse H
  • DNA ligase

Step one: separation of the two parental strands at the origin of replication

  • in order for the two parental strands to be replicated they must first be separated (or melt) in…


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