DNA Structure And Function

Question 1

Describe the process of DNA replication:

Answer 1

Process= catalysed by polymerase enzyme
Double helix unwinds — the hydrogen bonds holding the base pairs together break— allowing the two strands to break apart.
Free nucleotides in the nucleoplasm attach to their matching exposed base partner.

( semi conservative)

Question 2

What factors can cause damage to DNA?

Answer 2

External: Radiation, Chemicals
Internal: Replication stress, by products of cell metabolism

Question 3

What are the three main DNA repairs?

Answer 3

DNA mismatch repair ( when polymerase makes mistake )
Nucleotide repair (damage by UV light / chemicals )
Recombinational repair ( deals strand breaks)

Question 4

What is a missense mutation?

Answer 4

A point mutation that results in a codon that codes for a different amino acid.

Question 5

What is a nonsense mutation?

Answer 5

A mutation that causes a pre-mature stop-codon.