The principal constituents of proteins are amino acids, 20 of which are present in the body proteins in significant quantities. Figure 69-1 shows the chemical formulas of these 20 amino acids, demonstrating that they all have two features in common: each amino acid has an acidic group (—COOH) and a nitrogen atom attached to the molecule, usually represented by the amino group (—NH2).
Peptide Linkages and Peptide Chains. In proteins, the amino acids are aggregated into long chains by means of peptide linkages. The chemical nature of this linkage is demonstrated by the following reaction:
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.