**7.** The diagram shows the process of DNA replication, including the enzymes involved.
[VISUALIZATION: Diagram illustrating DNA replication fork. Show the double helix unwinding. Label: Helicase (unwinding DNA), Leading strand (synthesized continuously towards the fork), Lagging strand (synthesized discontinuously away from the fork), Okazaki fragments, DNA Polymerase III (adding nucleotides on both strands), DNA Polymerase I (replacing RNA primers), RNA primer, DNA Ligase (joining Okazaki fragments), Single-strand binding proteins. Indicate 5′ and 3′ ends clearly to show antiparallel nature and direction of synthesis.]
(a) Identify the enzyme responsible for unwinding the DNA double helix during replication. \[1]
(b) Explain why DNA replication is described as semi-conservative. \[2]
(c) Describe the role of complementary base pairing in DNA replication. \[3]
Question
Identify the enzyme responsible for unwinding the DNA double helix during replication. \[1]
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Look at the diagram provided or recall the first step in separating the DNA strands for replication.
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Explain why DNA replication is described as semi-conservative. \[2]
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Think about what ‘semi’ and ‘conservative’ mean in this context. How much of the original DNA molecule is kept in each new molecule?
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Each new DNA molecule consists of one original (parental/template) strand and one newly synthesized strand.
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Describe the role of complementary base pairing in DNA replication. \[3]
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Focus on the specific pairing rules (A with T, G with C) and explain how these rules ensure the genetic information is copied accurately.
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Complementary base pairing ensures accurate replication of the DNA sequence. Adenine (A) pairs specifically with Thymine (T), and Guanine (G) pairs specifically with Cytosine (C). This ensures that each template strand dictates the exact sequence of the new strand being synthesized.
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