DNA replication

Question 1

When does DNA replication occur and why?

Answer 1

Before cells divide (by mitosis or meiosis) the DNA must replicate to provide a copy for the new cell.

Question 2

How is the way DNA replicates described as and what does this mean?

Answer 2

The process of DNA replication is semi-conservative which is when in the daughter DNA (DNA being created) one strand is parental DNA (the original DNA that is being copied) and one strand is newly synthesised.

Question 3

Explain the steps for semi-conservative replication (of DNA)

Answer 3

1. The enzyme DNA helicase breaks the hydrogen bonds between the complementary base pairings between the two strands of DNA which causes the double helix structure to unwind.
2. Each of the separated strands acts as a template. Free floating DNA nucleotide’s withing the nucleus attach to their complementary base pairs on the template strands.
3. The enzyme DNA polymerase joins the adjacent nucleotide’s together to form the phosphodiester bonds via condensation reactions.
4. The two sets of daughter DNA contain one strand from the original (parental) DNA and one strand that is newly synthesised.