3: Replication of DNA

Question 1

3 possible models of DNA replication

Answer 1

Conservative, semi-conservative, dispersive

Question 2

Who proved the semiconservative model?
And how?

Answer 2

Meselson and Stahl.
The use of Nitrogen isotopes(14 and 15).

Question 3

Replication origins

Answer 3

Prokaryotes have one replication origin + 2 replication forks in different directions and Eukaryotes have multiple origins due to the size and length of DNA

Question 4

Direction of replication

Answer 4

New DNA strand made from 5’ to 3’, as DNA polyermerase can only synthesize in one direction

Question 5

What enzymes are needed in DNA replication?

Answer 5

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

Question 6

Causes of mutations

Answer 6

Insertion/ deletion, point mutation(substitution)