Q18 / 150 · MHT CET 2024 (10 May Shift 1) · Chemistry

Which from following statements is NOT true for nucleic acids?

  • A
    5' end of polynucleotide has free phosphate group.
  • Correct answer
    B
    Nucleic acids contain back bone formed of $-\mathrm{C}-\mathrm{O}-\mathrm{C}-$ linkage.
  • C
    Polynucleotide has free -OH group at $3^{\prime}$ end.
  • D
    Neighbouring nucleotides are bonded through phosphate diester linkage.

Solution

Option B is NOT true for nucleic acids. In nucleic acids, the backbone is formed by a sugar-phosphate linkage rather than a \(-\mathrm{C}-\mathrm{O}-\mathrm{C}-\) linkage. The backbone is composed of alternating sugar and phosphate groups, connected by phosphodiester bonds. Each phosphate group links the \(3^{\prime}\) carbon atom of one sugar molecule to the \(5^{\prime}\) carbon atom of the next sugar molecule, which forms the characteristic sugar-phosphate-sugar chain of DNA and RNA.

Hence, the correct answer is option: 'B'.

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