Question

Hydrolysis of nucleic acid gives nitrogenous base sugar and ________

• A. Sulphuric acid
• B. Phosphorous acid
• C. Sulphurous acid
• D. Phosphoric acid

Hint:

Nucleic acids are polymers of nucleotides.
Each nucleotide has three components: a nitrogenous base, a pentose sugar, and a phosphate group.
Complete hydrolysis of a nucleic acid breaks it down into these three constituent types.
The phosphate component in nucleic acids originates from phosphoric acid (H$_3$PO$_4$).

Answer 1

The Correct Option is D

Nucleic acids (DNA and RNA) are polymers of nucleotides. Each nucleotide unit consists of three components: 1. A nitrogenous base (purine or pyrimidine). 2. A pentose sugar (deoxyribose in DNA, ribose in RNA). 3. A phosphate group (derived from phosphoric acid). Nucleotides are linked together by phosphodiester bonds, which connect the 5' carbon of one sugar to the 3' carbon of the next sugar via a phosphate group. Hydrolysis of a nucleic acid breaks these phosphodiester bonds, as well as the N-glycosidic bonds linking the sugar to the base, and the ester bonds linking the phosphate to the sugar. Complete hydrolysis of a nucleic acid yields its fundamental components: \begin{itemize} \item Nitrogenous bases (Adenine, Guanine, Cytosine, Thymine/Uracil) \item Pentose sugar (Deoxyribose or Ribose) \item Phosphoric acid (H$_3$PO$_4$) (which exists as phosphate ions at physiological pH but is derived from phosphoric acid). \end{itemize} The question states that hydrolysis gives nitrogenous base, sugar, and \underline{\hspace{1cm}}. The missing component is the phosphate group, which is derived from phosphoric acid. Therefore, the correct answer is phosphoric acid. \[ \boxed{\text{Phosphoric acid}} \]