Which of the following nucleotide contains only ribose sugar and not deoxyribose?

The correct answer is Uracil – pentose sugar-phosphate.

To understand why this is the correct choice, let us look at the differences between the components of RNA (Ribonucleic Acid) and DNA (Deoxyribonucleic Acid):

1. Sugars in Nucleic Acids:
Nucleotides are the building blocks of nucleic acids, and each nucleotide consists of a nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group. RNA contains the pentose sugar ribose, whereas DNA contains the pentose sugar deoxyribose.

2. Nitrogenous Bases:
• Adenine, Cytosine, and Guanine are found in both DNA and RNA.
• Thymine is unique to DNA (which has deoxyribose sugar).
• Uracil is unique to RNA (which has ribose sugar).

3. Conclusion:
Since Uracil is only present in RNA, any nucleotide containing Uracil will contain ribose sugar and not deoxyribose. Cytosine is found in both, meaning a cytosine-containing nucleotide could contain either sugar depending on whether it is in DNA or RNA. Therefore, the nucleotide containing Uracil specifically contains only ribose sugar.