Question

Which one is an incorrect statement?

• A. The basic unit of DNA is nucleotide.
• B. A nitrogenous base is linked to pentose sugar by N – glycosidic linkage.
• C. Adenosine, guanosine and cytidine are nucleotides.
• D. DNA is the largest macromolecule of the cell.

Answer 1

Answer: (C)

In DNA, four types of nucleosides and four types of nucleotides are present. Nucleosides of DNA are adenosine, guanosine, cytidine and thymidine. At the same time, nucleotides of DNA are adenylic acid, guanylic acid, cytidylic acid and thymidylic acid. Exactly nucleosides and nucleotides of DNA are called 'Deoxyribonucleosides' and 'Deoxyribonucleotides' respectively.

DNA molecule is also called polynucleotide, so its basic unit is a nucleotide. A nitrogen base is attached on 1st carbon of deoxyribose sugar with the help of N-glycosidic bond. Among different biomolecules of the cell, DNA is the most abundant biomolecule.