DNA

• DNA

  • deoxyribonucleic acid
  • a molecule that carries genetic information - stored in nucleus
  • deoxyribose sugar + phosphate group + nitrogenous base
  • bases - thymine, adenine, cytosine, guanine
  • double helix anti parallel structure - 5' to 3'
  • triplet codon codes for specific amino acids
• DNA replication

  • hydrogen bonds are broken apart by helicase enzyme
  • free nucleotides surround the molecule and bind to their complementary bases via hydrogen bonding
  • DNA polymerase catalyses the reaction
• semi conservative replication = DNA is now made up from one original strand and a new complementary strand
• components of DNA replication:

  • gyrase - untwists the double helix
  • helicase - unzips the DNA, breaks the hydrogen bonds
  • primase - adds the RNA primer
  • DNA polymerase - adds new fragments, hydrogen bonding
  • ligase - joins the Okazaki fragments together
  • exonuclease - removes the RNA primer
  • topoisomerase - stops the replicated DNA from over winding
  • single stranded binding proteins - hold the replication bubble open