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In nucleic acids, the heterocyclic bases...

In nucleic acids, the heterocyclic bases are connected to `D`-ribofuranose by a covalent bond between the `N` atom of the heterocyclic ring and the - of the sugar through a `beta`-linkage, i.e., by replacing the `beta-OH` group of the latter.

A

`C - 3'`

B

`C - 1'`

C

`C - 5'`

D

`C - 2'`

Text Solution

Verified by Experts

The correct Answer is:
B
The central portion of the nucleotide is the monosaccharide, and it is always present as a five membered ring, that is, as a furanoside. The heterocyline base of a nucleotide is attached through an `N`- glycoside linkage to `C -1'` of the ribose or deoxyribose unit and this linkage is always `beta`. In a nucleotide, the phosphate linkage is usually attached `C - 5'` of the sugar. The successive nucleotides of both `DNA` and `RNA` are covalently linked to each other through a phosphodiester linkage formed between `C - 5` hydroxyl group of the pentose of one nucleotide group. Thus, the phosphate group of a nucleotides is present as a phosphate ester and may be attached at `C - 5'` or `C - 3'`
Note that, in nucleotide, the carbon atoms of the monosaccharide protein portion are designated with primed numbers, i.e., `1',2',3'`, etc
Removal of the phosphate group of a nucleotide converts it to a compound known as a nucleoside.
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