If asked to build a model of an amino acid, you would need parts to represent which of the following groups?

• A. An amino group, a carboxyl group, a hydrogen atom, and a unique R group attached to a central carbon
• B. A phosphate group, a methyl group, and a ribose sugar
• C. A benzene ring, a phosphate group, and a fatty acid chain
• D. Two carboxyl groups and a sulfur atom

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the structure of an amino acid. Amino acids are the building blocks of proteins and share a common structure. Each amino acid consists of a central carbon atom (called the alpha carbon) to which four groups are attached.
2. Step 2: Identify the four groups attached to the central carbon in an amino acid. These include: (1) an amino group (-NH₂), (2) a carboxyl group (-COOH), (3) a hydrogen atom, and (4) a unique side chain (R group) that varies for each amino acid.
3. Step 3: Compare the options provided in the problem to the structure of an amino acid. The correct option should include the amino group, carboxyl group, hydrogen atom, and unique R group attached to the central carbon.
4. Step 4: Eliminate the incorrect options. For example, a phosphate group, methyl group, and ribose sugar are components of nucleotides, not amino acids. Similarly, a benzene ring, phosphate group, and fatty acid chain are characteristic of lipids, not amino acids. Two carboxyl groups and a sulfur atom do not represent the standard structure of an amino acid.
5. Step 5: Conclude that the correct answer is the option describing an amino group, a carboxyl group, a hydrogen atom, and a unique R group attached to a central carbon, as this matches the fundamental structure of an amino acid.