Question

The bonding between sugar and base in a DNA nucleotide is

• A. Hydrogen bonding
• B. Disulfide bonding
• C. N-glycosidic bonding
• D. Ester linkage

Hint:

Nucleic Acid Chemical Bonds:
Sugar to Base = $\beta$-N-GLYCOSIDIC BOND.
Sugar to Phosphate = Phosphodiester bond.
Base to Base (Complementary) = Hydrogen bonds.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Molecular biochemistry of nucleic acids: a covalent $eta$-N-glycosidic bond links the C-1' carbon of 2'-deoxyribose to the N-9 atom of purines or N-1 atom of pyrimidines.
Key Formula or Approach:
\[ \text{Nucleoside Formation: } \text{Deoxyribose C-1'} + \begin{cases} \text{Purine (A, G) N-9} \text{Pyrimidine (C, T) N-1} \end{cases} \xrightarrow{-\text{H}_2\text{O}} \mathbf{\beta\text{-N-Glycosidic Bond}} \]

Step 2: Detailed Explanation:
In nucleic acid structure and molecular biology:
1. N-Glycosidic Bond (C): The covalent linkage joining the C-1' carbon atom of the pentose sugar (2'-deoxy-D-ribose in DNA) to the nitrogenous base (specifically to the N-9 nitrogen atom of purines [adenine, guanine] or to the N-1 nitrogen atom of pyrimidines [cytosine, thymine]).
2. Phosphodiester Linkage: Joins the 3'-OH and 5'-phosphate groups along the sugar-phosphate backbone.
3. Hydrogen Bonding: Links complementary bases across double strands (A=T, G$\equiv$C).

Step 3: Final Answer:
Therefore, the bonding between sugar and base is N-glycosidic bonding, matching option (C).