3: Replication of DNA Flashcards
3 possible models of DNA replication
Conservative, semi-conservative, dispersive
Who proved the semiconservative model?
And how?
Meselson and Stahl.
The use of Nitrogen isotopes(14 and 15).
Replication origins
Prokaryotes have one replication origin + 2 replication forks in different directions and Eukaryotes have multiple origins due to the size and length of DNA
Direction of replication
New DNA strand made from 5’ to 3’, as DNA polyermerase can only synthesize in one direction
What enzymes are needed in DNA replication?
DNA helicase: unwind parental double helix
Topoisomerase: helps unwind the two strands of DNA
Primase: synthesis of RNA primer
DNA pol III: synthesize the leading strand and Okazaki fragments from 5’ to 3’
DNA pol I: exonuclease activity in both directions
DNA ligase: ligate gaps between adjacent Okazaki fragments
Causes of mutations
Insertion/ deletion, point mutation(substitution)