DNA is a helical structure where different nucleotides are joined by a phospodiester bond. While base pairs from opposite strands are joined by hydrogen bond. They help in stabilizing DNA molecule. N-glycosidic linkage in DNA, is the nitrogen carbon linkage between the nitrogen of purine or pyrimidine bases and the carbon of the sugar group. This bond does not provide stability.

So, the correct answer is "N-glycosidic lknkage"...

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Answer:

N- glycosidic linkage does not confer stability to the helical structure of DNA.

Explanation:

The helical structure of DNA is stabilized by several factors such as the phosphodiester bond, hydrogen bond, and base stacking interactions. Let's discuss each of these factors in detail.

Phosphodiester Bond:

The phosphodiester bond is formed between the 3' hydroxyl group of one sugar molecule and the 5' phosphate group of the adjoining sugar molecule. This bond forms the backbone of the DNA molecule and helps in holding the nucleotides together. The phosphodiester bond confers stability to the helical structure of DNA.

Hydrogen Bond:

The hydrogen bond is formed between the nitrogenous bases of the two complementary strands of DNA. Adenine always pairs with thymine through two hydrogen bonds, while guanine pairs with cytosine through three hydrogen bonds. The hydrogen bond between these base pairs helps in holding the two strands of DNA together and confers stability to the helical structure of DNA.

Base Stacking Interactions:

The nitrogenous bases of DNA are planar and aromatic. These bases stack on top of each other and form a hydrophobic interaction. This interaction helps in stabilizing the helical structure of DNA.

N- glycosidic linkage:

The N-glycosidic linkage is a covalent bond between the nitrogenous base and the 1' carbon of the sugar molecule. This bond is responsible for attaching the nitrogenous base to the sugar molecule. However, it does not confer stability to the helical structure of DNA.

Conclusion:

In summary, the stability of the helical structure of DNA is conferred by the phosphodiester bond, hydrogen bond, and base stacking interactions. The N-glycosidic linkage does not play a significant role in conferring stability to the helical structure of DNA.