DNA Replication

• DNA Replication (general)

  • duplicates the code DNA carries
  • in eukaryotic cells, chromosomes become double stranded
  • occurs in the preparation for all cell division
  • occurs during the S phase of the cell cycle
  • semi-conservative (each strand in the double helix acts as a template strand for the synthesis of a new, complementary strand)
  • DNA is synthesised in a 5' to 3' direction
• DNA Replication (process)

  Step 1:

  • DNA helicase separates the double strand by breaking the weak hydrogen bonds
  • each half of the parent molecule is used as a template

  Step 2:

  • enzyme primase attaches a primer (a short sequence of RNA), to show DNA polymerase where to start adding nucleotides

  Step 3:

  • DNA polymerase adds complementary nucleotides
  • synthesis of the new daughter strand in a 5' to 3' direction

  Step 4:

  • production of 2 identical DNA molecules made up of 1 parent strand and 1 daughter strand