**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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Which enzyme ‘unzips’ the DNA by breaking the hydrogen bonds between base pairs?
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Explain why DNA replication is described as semi-conservative. \[2]
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Consider the composition of the two DNA molecules produced after replication relative to the original molecule. What does ‘semi’ mean?
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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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How does the cell ensure the new DNA strand has the correct sequence? Mention the specific base pairs (A, T, C, G) and how they interact.
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Complementary base pairing ensures accurate replication of the base sequence. Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). Each template strand dictates the sequence of the new strand.
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