Amino acids are the fundamental building blocks of proteins, functioning as monomers that link together to form protein polymers. Each amino acid consists of common components and a unique side chain known as the R group. Living organisms utilize 20 different amino acids, each characterized by these common components and distinct R groups.

The structure of an amino acid includes a central carbon atom, referred to as the alpha carbon, which is surrounded by several key components. At the top of the alpha carbon is a hydrogen atom, which is consistent across all amino acids. To the left of the alpha carbon is an amino group (–NH₂), representing the N-terminal end of the amino acid, while to the right is a carboxyl group (–COOH), marking the C-terminal end. These components are essential and shared among all amino acids.

The unique aspect of each amino acid lies in its R group, which varies from one amino acid to another. This R group can range from a simple hydrogen atom to more complex structures with multiple atoms, contributing to the diverse properties of the amino acids. Understanding these components is crucial, as they determine the characteristics and functions of proteins formed from these amino acids.

In summary, while it is not necessary to memorize all 20 amino acids for a biology class, recognizing that there are 20 distinct amino acids, each with a common backbone and unique R group, is essential for grasping the basics of protein structure and function.