Final answer:
Amino acids have four major components: an amino group, a carboxyl group, a hydrogen atom, and an R group. Amino acids can be grouped based on the physical and chemical properties of their R groups.
Step-by-step explanation:
An amino acid consists of four major components: an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and an R group which varies among different amino acids. The R group determines the physical and chemical properties of the amino acid. Amino acids can be classified based on the properties of their R groups, such as whether they are nonpolar, polar but uncharged, negatively charged, or positively charged.