DNA replication

• Describe semi-conservative replication in detail

  1. DNA helices breaks the hydrogen bonds between bases on the two polynucleotide strands- this makes the helix unwind to from two single strands

  2. each original strand acts as a template for a new strand.free floating nucleotides are attracted to the complimentary exposed bases due to complimentary base pairing

  3. condensation reactions join the nucleotide strands together catalysed by DNA polymerase. hydrogen bonds from between bases of the two strands

  4. each molecule contains one old strand and one new strand
• What direction do strands in a DNA helix run

  Antiparalell - oposite directions
• how does DNA polymerase move along a DNA strand and why

  - the active site of DNA polymerase is only complimentary to the 3' (3 prime) end of the new nucleotide so can only add nucleotides to the strand at the 3 prime end

  - DNA polymerase moved down the template strand in a 3' to 5' direction
• what direction is the new strand made in

  - the new stand is made in a 5' to 3' direction
• What direction does DNA polymerase move in

  - DNA polymerase moved down the template strand in a 3' to 5' direction
• what is the hypothesis for conservative replication


  the original DNA remains intact following DNA replication and the two newly synthesised strands join together
• what is the hypothesis for Dispersive replication of DNA

  the original DNA is broken apart and sections of new DNA are put in place of it
• 3 hypothesis of DNA replication