HUMAN NUTRITION

Detailed explanation-1: -Proteins are organic molecules, simpler than cells though not formally “alive” in any sense of the word. They consist of one or more amino acids, which are simple organic molecules that appear in nature where no life is observed. Amino acids have even been observed in space-in one instance, on an icy comet.

Detailed explanation-2: -A protein molecule is made from a long chain of these amino acids, each linked to its neighbor through a covalent peptide bond (Figure 3-1). Proteins are therefore also known as polypeptides. Each type of protein has a unique sequence of amino acids, exactly the same from one molecule to the next.

Detailed explanation-3: -A peptide is a short chain of amino acids (typically 2 to 50) linked by chemical bonds (called peptide bonds). A longer chain of linked amino acids (51 or more) is a polypeptide.