2.2 DNA replication

Question 1

What are the two main stages of cell division?

Answer 1

• nuclear division

- cytokinesis

Question 2

What are the 4 requirements for semi-conservative replication?

Answer 2

• the 4 types of nucleotide with bases A, G, C,
• both strands of DNA molecule act as a template the attachment of the nucleotides.
• DNA polymerase
• A source of chemical energy

Question 3

Describe the process of semi-conservative replication.

Answer 3

1) DNA helicase breaks H bonds linking base pairs of DNA
2) Double helix separates into two strands and unwinds
3) Exposed polynucleotides strands act as a template to which complimentary free nucleotides bind by specific base pairing
4) Nucleotides are joined in a condensation reaction by DNA polymerase to form the ‘missing’ polynucleotide strand on the original strands of DNA
5) Each new DNA molecule contains one of the original DNA strands.

Question 4

What is the role of DNA helicase?

Answer 4

To break hydrogen bonds linking base pairs of DNA

Question 5

What is the role of DNA polymerase?

Answer 5

To catalyse the condensation reaction joining the nucleotides with H bonds.