Nucleotide is obtained by linking nucleoside to phosphoric acid at which position of sugar?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 5'
Nucleic acids are built in three levels:
Nucleoside = base + sugar. The base is attached at C1′ of the sugar.
Nucleotide = nucleoside + phosphoric acid. The phosphate is linked at C5′ of the sugar.
Nucleic acid: nucleotides join through 3′–5′ phosphodiester linkages between the sugar of one nucleotide and the phosphate of the next.
The primes (′) number the carbons of the sugar, to tell them apart from the atoms of the base. So in forming a nucleotide, phosphoric acid is attached at the 5′ position of the sugar.
NCERT (2026-27 edition):
Structure of Nucleic Acids
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| 25-05 S1 | 28-05 S2 | – | – | – |