Question

The type of linkage present between nucleotides is:

• A. Phosphoester linkage
• B. Phosphodiester linkage
• C. Amide linkage
• D. Glycosidic linkage

Hint:

Nucleotides are linked by phosphodiester bonds, forming the backbone of DNA and RNA.

Answer 1

The Correct Option is B

The given question asks about the type of linkage present between nucleotides. To tackle this question, we need to understand the structure of nucleic acids, which are made up of nucleotides.

Understanding Nucleotides and Their Linkages

A nucleotide consists of three components:

• A nitrogenous base (adenine, thymine, cytosine, guanine, or uracil)
• A five-carbon sugar (either ribose or deoxyribose)
• A phosphate group

Nucleotides are linked together to form nucleic acids (DNA or RNA). The linkage between the nucleotides is crucial for the formation of the sugar-phosphate backbone of these molecules:

Type of Linkage in Nucleotides

The linkage between nucleotides is called a phosphodiester linkage. This bond forms when the phosphate group of one nucleotide forms a covalent bond with the hydroxyl group on the sugar of the next nucleotide. This process creates a repeating sugar-phosphate backbone, which is the structure that defines nucleic acids like DNA and RNA.

Here's how the linkage occurs:

• The 3'-hydroxyl group (OH group) of one sugar joins with the 5'-phosphate group of the next sugar, forming a phosphodiester bond.
• This reaction releases a water molecule, commonly seen in condensation reactions.

Conclusion

Thus, the correct answer is Phosphodiester linkage. This type of bond ensures the structural integrity and continuity of nucleic acids.

Explanation of Incorrect Options

• Phosphoester linkage: This linkage is involved in forming a single ester bond with the phosphate, but it does not describe the linkage between two nucleotides.
• Amide linkage: Typically forms between amino acids in proteins as a peptide bond, not in nucleic acids.
• Glycosidic linkage: Seen in carbohydrates where a sugar forms a bond with another molecule; it's not the linkage between nucleotides.