The step(s) that occur(s) during DNA replication is/are:I. Breakage of phosphodiester bonds.II. Breakage and reformation of hydrogen bonds.III. Binding of free nucleotides with their complementary bases.
Correct answer: D. II and III
- A. I only
- B. I and II
- C. III only
- D. II and III
Explanation
The correct answer is II and III. During DNA replication, the hydrogen bonds between the base pairs of the two DNA strands are temporarily broken to allow the strands to separate. This separation allows free nucleotides to pair with their complementary bases on each template strand, forming new hydrogen bonds. However, phosphodiester bonds, which form the backbone of the DNA strand, are not broken during this process. Therefore, Option II and III correctly describe the steps in DNA replication, while Option I is incorrect.
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About Structure of DNA
DNA structure includes nucleotides made of deoxyribose, phosphate and nitrogenous bases, arranged in two antiparallel polynucleotide strands. Questions cover the double helix, phosphodiester and hydrogen bonds, complementary base pairing between adenine and thymine and between guanine and cytosine, and the significance of major and minor grooves.
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