DNA Replication

Question 1

Name two scientist who proposed models of the chemical structure of DNA and of DNA replication

1 mark

Answer 1

Watson and Crick

Question 2

Using your knowledge of semi conservative replication of DNA to suggest

1. The role of single stranded DNA fragments
2. The role of the DNA nucleotides

3 marks

Answer 2

1)
1. Template
2. Determine order of nucleotides/ bases

2)
3. Forms complementary pairs /
A-T, C-G
Or
Forms complementary DNA strand

Accept sequence / chain for strand

Question 3

Key points

Answer 3

The semi-conservative replication of DNA ensures genetic continuity between generations of cells.

The process of semi-conservative replication of DNA in terms of:
• unwinding of the double helix

• breakage of hydrogen bonds between complementary bases in the polynucleotide strands

• the role of DNA helicase in unwinding DNA and breaking its hydrogen bonds

• attraction of new DNA nucleotides to exposed bases on template strands and base pairing

• the role of DNA polymerase in the condensation reaction that joins adjacent nucleotides.

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Students should be able to evaluate the work of scientists in validating the Watson-Crick model of DNA replication.