Biomolecules

Two nucleotides are joined together by a linkage known as :

1. Phosphodiester linkage
2. Glycosidic linkage
3. Disulphide linkage
4. Peptide linkage

Answer

(1) Phosphodiester linkage

Solution

The phosphate of one nucleotide (at C-5′ of its sugar) forms an ester with the 3′-OH of the sugar of the next nucleotide:

Sugar(3')-O- OH | O \|P-O-(5')Sugar

∵ one P forms two P–O–C ester bonds ⇒ phosphodiester linkage

(B): glycosidic link joins base–sugar or sugar–sugar ⇒ (B) is not the nucleotide link

(C): disulphide (–S–S–) joins cysteine units of proteins ⇒ (C) is not

(D): peptide (–CO–NH–) joins amino acids ⇒ (D) is not

Answer: (1)