A nitrogenous base is linked to the 'OH' of 1' C pentose sugar through:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → N-glycosidic linkage
(1) Phosphodiester bond — Incorrect. This bond joins one nucleotide to the next. It runs between the 3′-OH of one sugar and the 5′ phosphate of the next one. It forms the backbone of the DNA strand, not the link between base and sugar.
(2) N-glycosidic linkage — Correct. A nitrogenous base is joined to the 1′ carbon of the pentose sugar through its nitrogen atom. This is an N-glycosidic linkage. The base and sugar together form a nucleoside, such as adenosine or guanosine.
(3) O-glycosidic linkage — Incorrect. An O-glycosidic link joins sugar molecules through oxygen, as in a disaccharide. The base is joined through its nitrogen, so the link is N-glycosidic.
(4) Peptide linkage — Incorrect. A peptide bond joins amino acids in a protein.
NCERT Extract:
Structure of Polynucleotide Chain – …
