2.2 — DNA replication

Question 1

what process in DNA copied by?

Answer 1

semi-conservative replication

Question 2

what does semi-conservative replication of DNA produce?

Answer 2

DNA molecules consisting of one original DNA strand and one newly synthesised DNA strand

Question 3

what are the stages of semi-conservative replication in DNA?

Answer 3

1. DNA molecule is ready to be replicated
2. the enzyme DNA helicase breaks down hydrogen between complimentary bases. this unwinds the double helix and separates the strands.
3. each strand acts as a templates as free nucleotides attract to their complimentary bases. (A+T, C+G)
4. the enzyme DNA polymerase joins the free nucleotides together via condensation reaction in the 5’ to 3’ direction. this forms phosphodiester bonds to create the sugar-phosphate backbone of the new DNA strand
5. two identical copies of DNA are made. each copy is made up of one of the original (template) strands and one newly synthesised DNA strand

Question 4

what enzyme breaks the hydrogen bonds between the complimentary bases?

Answer 4

DNA helicase

Question 5

what does DNA helicase breaking the DNA strands’ hydrogen bonds do?

Answer 5

unwinds the double helix and separates the strands

Question 6

what does the template strands in DNA replication attract?

Answer 6

complimentary bases that are free floating nucleotides