DNA replication is a semi-conservative process whereby pre-existing strands act as templates for newly synthesised strands

• The process of DNA replication is coordinated by two key enzymes – helicase and DNA polymerase
  

Helicase

• Helicase unwinds the double helix and separates the two polynucleotide strands
  

• It does this by breaking the hydrogen bonds that exist between complementary base pairs
  

• The two separated polynucleotide strands will act as templates for the synthesis of new complementary strands
  

DNA Polymerase

• DNA polymerase synthesises new strands from the two parental template strands
  

• Free deoxynucleoside triphosphates (nucleotides with 3 phosphate groups) align opposite their complementary base partner
  

• DNA polymerase cleaves the two excess phosphates and uses the energy released to link the nucleotide to the new strand