Replication

• DNA Replication

  • Initiation - unwinding of DNA by unzipping it by DNA Helicase, separated strands will acts as a template
  • Elongation - two strands are replicated differently because they run in opposite directions, leading strand is oriented towards the fork and lagging strands oriented away from the fork
  • Termination - Once bases are matched up, exonuclease strips away the primers. DNA polymerase proofreads and seals the gap from the primers. DNA Ligase seals back the two strands
• Replication of Leading Strand

  • RNA Primer binds to 3' of the leading strands as starting point for the synthesis
  • DNA polymerase binds and walks along the strands towards replication fork
  • As it reads, it adds complementary bases (A w/ T, C w/ G)
  • The replication is continuous
• Replication of Lagging Strand

  • DNA polymerase can only copy small lengths because it runs on the opposite direction
  • RNA primers binds at various points along the strand and polymerase reads from these points and adds complementary base pairs creating Okazaki fragments. This is called discontinuous replication
  • The fragments are then joined up to make continuous sequence