Question

Choose the correct answer from the alternatives given :
In a DNA strand the nucleotides are linked together by

• A. Glycosidic bonds
• B. Phosphodiester bonds
• C. Peptide bonds
• D. Hydrogen bonds

Answer 1

The correct option is B Phosphodiester bonds

A nucleotide has three components - nitrogenous base, a pentose sugar ribose in case of RNA and deoxyribose for DNA) and a phosphate group. There are two types of nitrogenous bases - Purines (Adenine and Guanine) and Pyrimidines (Cytosine and Thymine). A nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage to form a nucleoside. When a phosphate group is linked to 5 -OH of a nucleoside through phosphodiester linkage, a corresponding nucleotide is formed. The nucleotides are linked through 3-5 phosphodiester linkage to form a dinucleotide.

So, the correct answer is 'Phosphodiester bonds'.