Consider the given table related to four DNA nucleotides (I, II, III and IV).During DNA duplication, the nucleotide that can pair with an adenine base is
Correct answer: A. I
- A. I
- B. II
- C. III
- D. IV
Explanation
Adenine pairs with thymine in DNA replication. Thymine has a single ring in its structure, and the carbon-to-oxygen ratio in pentose is 1:1 (as thymine is present in DNA only, and deoxyribose has one oxygen less than ribose (normal pentose)). So option A is correct. All other options incorrectly describe the structure of thymine.
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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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