Amino acids are classified as acidic, basic, or neutral based on the relative number of amino and carboxyl groups in their molecules. Equal numbers result in neutrality, more amino groups make them basic, and more carboxyl groups make them acidic.

Amino acids are generally represented by both three-letter and one-letter symbols. Examples mentioned in the paragraph include glycine, tyrosine, and others, each with their corresponding structures and symbols.

Glycine is named for its sweet taste (glykos means sweet in Greek), and tyrosine is named as it was first obtained from cheese (tyros means cheese in Greek). Trivial names often reflect the properties or sources of the compounds.

Amino acids are classified as α, β, γ, δ, etc., based on the relative position of the amino group with respect to the carboxyl group. Only α-amino acids are obtained on the hydrolysis of proteins.

Proteins, the most abundant biomolecules in living systems, are crucial for the structure and functions of life, required for growth and maintenance of the body. Chief sources of proteins in the diet include milk, cheese, pulses, peanuts, fish, and meat.