HESI A2 Biology Practice Test 2026 – All-in-One Study Guide for Exam Success!

The basic structure of an amino acid consists of an amino group, a carboxyl group, and a variable side chain known as the R group. The amino group (-NH2) gives amino acids their name and is essential for the formation of proteins. The carboxyl group (-COOH) contributes to the acidic nature of amino acids and is involved in peptide bond formation during protein synthesis. The R group is unique for each amino acid and determines its properties, such as polarity, charge, and overall structure, thus influencing the protein's function and shape. This fundamental structure is crucial in biochemistry, as amino acids are the building blocks of proteins, which are essential for a wide range of cellular functions and processes in living organisms.