Kaplan Nursing Entrance Practice Exam

What is a nucleotide comprised of?

1. Two sugars and a phosphate

2. A 3-carbon sugar base

3. Single amino acid

4. Complex lipid structure

The correct answer is: A 3-carbon sugar base

A nucleotide is a fundamental building block of nucleic acids, such as DNA and RNA. It consists of three main components: a five-carbon sugar, a phosphate group, and a nitrogenous base. The sugar in a nucleotide can either be ribose (in RNA) or deoxyribose (in DNA). This is why the chosen answer focuses on the sugar component; however, the specific terminology used in the answer might be somewhat misleading since nucleotides actually contain a five-carbon sugar and detailed recognition of that component is important. The correct structure of a nucleotide is crucial for understanding its role in genetic material. The phosphate group is linked to the sugar molecule, and the nitrogenous base is attached to the sugar. This combination forms the backbone of DNA and RNA structures and plays a vital role in the nucleotide's overall functionality. Recognizing these basic structural elements is essential when studying molecular biology and genetics, as they are the precursors to the formation of complex nucleic acids that encode genetic information.