What are the building blocks of proteins?

• A. Amino acid
• B. mRNA
• C. Mutation
• D. 5-carbon sugar

Answer: (A)

Amino acids are the building blocks of proteins because proteins are polymers formed by linking amino acids together through peptide bonds to create long chains that fold into functional shapes. Each amino acid has a common backbone with an amino group and a carboxyl group, plus a unique side chain (the R group) that gives it specific properties. The sequence of amino acids in a protein determines how it folds and what it can do in the cell, from structural support to catalyzing reactions.

mRNA plays the role of a template that specifies the order of amino acids during protein synthesis, but it is not a building block itself. Mutations are changes in genetic information that can alter which amino acids appear in a protein or how much protein is made. A 5-carbon sugar is a part of nucleotides in DNA and RNA, not a component of proteins.