DNA Replication Model by Watson-Crick — NEET
📚 Practice ConceptWhile proposing the double helical structure for DNA, Watson and Crick had immediately proposed a scheme for replication of DNA. To quote their original statement that is as follows:
Which of the following statements regarding the structure and replication of DNA are correct? S1: Watson and Crick's proposition of DNA replication immediately followed their elucidation of the double helix structure, suggesting a copying mechanism for genetic material. S2: The chemical stability of DNA is enhanced by the presence of a 2'-OH group at every nucleotide, making it less reactive than RNA. S3: Complementary base pairing ensures that each parental DNA strand can accurately serve as a template for synthesizing new identical strands, leading to semiconservative replication. S4: DNA-dependent DNA polymerases can initiate the process of replication at any random location along the DNA molecule. S5: The experimental proof for semiconservative DNA replication was first demonstrated in higher organisms like Vicia faba, and later confirmed in prokaryotes like E. coli.
View solution & NCERT explanation
Correct answer: B — S1 and S3 are correct
The core concept here relates to the structure of DNA and its direct implications for replication, as proposed by Watson and Crick, and the experimental proof for semiconservative replication. S1: This statement is correct. Watson and Crick explicitly noted that the specific pairing in their double helix model immediately suggested a copying mechanism for genetic material. (NCERT Ref: Page 88, Para 1) S2: This statement is incorrect. The presence of a 2'-OH group is characteristic of RNA, making RNA more reactive and less stable than DNA. DNA *lacks* this 2'-OH group, contributing to its chemical stability. (NCERT Ref: Page 87, Para 3) S3: This statement is correct. Complementary base pairing is the fundamental principle that allows each strand to serve as a template, ensuring that the two newly produced DNA molecules are identical to the parental DNA. (NCERT Ref: Page 81, Para 4; Page 88, Para 1) S4: This statement is incorrect. DNA replication does not initiate randomly but at definite regions called origins of replication. DNA polymerases also cannot initiate replication on their own. (NCERT Ref: Page 90, Para 4) S5: This statement is incorrect. Semiconservative replication was first proven in Escherichia coli by Meselson and Stahl, and then confirmed in higher organisms like Vicia faba by Taylor and colleagues. The order is reversed in the statement. (NCERT Ref: Page 88, Para 2; Page 90, Para 1) Therefore, only statements S1 and S3 are correct.
What does NCERT say about While proposing double helical?
Has this concept appeared in NEET?
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.