In the structure of DNA, which pentose sugar is present in the nucleotide backbone?

• A. fructose
• B. glucose
• C. ribose
• D. 2-deoxyribose

Answer: (D)

Verified step by step guidance

1. Recall that DNA stands for deoxyribonucleic acid, which indicates the type of sugar present in its nucleotides.
2. Understand that nucleotides in DNA consist of three components: a phosphate group, a nitrogenous base, and a pentose sugar.
3. Identify that the pentose sugar in DNA is a five-carbon sugar lacking one oxygen atom compared to ribose, hence called 2-deoxyribose.
4. Contrast this with RNA, which contains ribose as its pentose sugar, having an -OH group on the 2' carbon.
5. Conclude that the pentose sugar in the DNA backbone is 2-deoxyribose, not fructose or glucose, which are not components of nucleic acid backbones.