6.2 DNA Replication

Describe the mechanisms by which genetic information is copied for transmission between generations.

• DNA replication ensures continuity of hereditary information.
  • i. DNA is synthesized in the 5’ to 3’ direction.
  • ii. R eplication is a semiconservative proc ess, meaning one strand of DNA serves as the template for a new strand of complementary DNA.
  • iii. Helicase unwinds the DNA strands.
  • iv. T opoisomerase relaxes supercoiling in front of the r eplication fork.
  • v. DNA polymerase requires RNA primers to initiat e DNA synthesis.
  • vi. DNA polymerase synthesizes new strands of DNA c ontinuously on the leading strand and discontinuously on the lagging strand.
  • vii. Ligase joins the fragments on the lagging strand.
  • Exclusion: The names of the steps and particular enzymes involved, excluding DNA polymerase, ligase, RNA polymerase, helicase, and topoisomerase, are beyond the scope of the AP Exam.