Question

A nucleotide is composed of

• A. Nitrogenous base, pentose sugar, and phosphoric acid
• B. Nitrogenous base, hexose sugar, and phosphoric acid
• C. Nitrogenous base and hexose sugar
• D. Nitrogenous base and pentose sugar

Answer 1

The correct option is A Nitrogenous base, pentose sugar, and phosphoric acid

Nucleotides are the monomeric units of nucleic acid. It consists of three components:
1. A pentose sugar (ribose or deoxyribose)
2. A nitrogenous base
3. A phosphoric acid

In the case of DNA, the sugar is deoxyribose and in RNA it is ribose. The nitrogenous bases are of two types:
1. Purines
- Adenine
- Guanine
2. Pyrimidines
- Cytosine
- Thymine
- Uracil
DNA has purines (Adenine and Guanine) and pyrimidines (Cytosine and Thymine) while RNA has purines (Adenine and Guanine) and pyrimidines (Cytosine and Uracil)
The phosphoric acid contains high energy bonds (Phospho-anhydride bonds) energy of which is used for the polymerization reaction of nucleotides.

Structure of a nucleotide