Biology Regents Practice Exam 2025 - Free Practice Questions and Study Guide

The sequence and properties of amino acids are crucial in determining a protein's structure and function. Each amino acid has unique side chains, or R groups, that impart specific chemical properties, such as hydrophobicity or charge. The order in which amino acids are linked together forms a specific primary structure that folds into higher-order structures (secondary, tertiary, and quaternary) dictated by the interactions between the amino acid side chains.

This folding is vital because a protein's shape determines how it interacts with other molecules, including substrates, other proteins, and nucleic acids. For example, enzymes are proteins that catalyze biochemical reactions, and their active sites are specifically shaped to fit particular substrate molecules. If the sequence of amino acids changes, it can alter the protein's shape, potentially impairing its function or completely changing its role within the cell.

In contrast, while the length of the amino acid chain, the type of amino acids, and other factors may play a role, they do not capture the comprehensive link between amino acid sequence and protein structure/function. Thus, the correct understanding of protein function is centered on the sequence and properties of the amino acids.