Which three components make up a nucleotide?

• A. A phosphate group, a fatty acid, and a nitrogenous base
• B. A phosphate group, a five-carbon sugar, and a nitrogenous base
• C. A ribose sugar, a carboxyl group, and a nitrogenous base
• D. A deoxyribose sugar, a glycerol molecule, and a phosphate group

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the structure of a nucleotide. A nucleotide is the basic building block of nucleic acids like DNA and RNA. It consists of three main components: a phosphate group, a five-carbon sugar, and a nitrogenous base.
2. Step 2: Identify the role of each component. The phosphate group contributes to the backbone of the nucleotide chain, the five-carbon sugar (either ribose in RNA or deoxyribose in DNA) provides structural support, and the nitrogenous base (adenine, thymine, cytosine, guanine, or uracil) carries genetic information.
3. Step 3: Eliminate incorrect options. For example, fatty acids, carboxyl groups, and glycerol molecules are not part of nucleotide structure; they are associated with lipids and other biomolecules.
4. Step 4: Match the correct components to the nucleotide structure. The correct combination is a phosphate group, a five-carbon sugar, and a nitrogenous base.
5. Step 5: Confirm the answer by reviewing the molecular structure of nucleotides in DNA and RNA to ensure the components align with the correct biological function.