Biology - Cell Cycle and Mitosis

Question 1

What is DNA replication?

Answer 1

Process by which DNA makes an exact copy of itself.

Question 2

Semi-conservative theory of replication

Answer 2

A newly formed DNA molecule consists of one original strand and one newly synthesised strand.

Question 3

DNA Replication

Answer 3

1. Helicase unwinds and unzips the DNA double helix, separating the two parent strands of the DNA molecule from one another by breaking the hydrogen bonds between complementary base pairs.
2. Each strand then acts as a template for synthesising a new strand of DNA. RNA primase adds an RNA primer at the 3’ end so DNA polymerase can attach to the template strands.
3. Then DNA Polymerase copies the DNA template strands, moving 3’ to 5’, by joining up free DNA nucleotides by complementary base pairing.
4. DNA ligase joins any gaps in the sugar phosphate backbone of the Okazaki fragments. Two identical copies of DNA are produced.