Protein synthesis is a two-step process that individual cells undergo to manufacture proteins necessary to their survival. Specific enzymes within a cell's nucleus initiate protein synthesis by unwinding sections of deoxyribonucleic acid (DNA) for ribonucleic acids (RNA) to read, which then synthesizes a single strand of messenger RNA (mRNA) that leaves the nucleus and joins with ribosomes in the cytoplasm. Protein synthesis occurs through the formation of amino acids.
Proteins are heavily relied upon in the body and have a role in virtually all cell functions. Structural proteins provide cellular support. Keratin, collagen and elastin are a few examples of structural proteins. Keratin is found in hair, quills, feathers, horns and beaks while collagens and elastins comprise tendons and ligaments. Antibodies used by the immune system for defense against bacteria, viruses and other foreign intruders are a type of specialized protein. Actin and myosin are contractile proteins used in muscle contraction and movement. Enzymes such as lactase and pepsin are catalyst proteins that speed up chemical reactions in the body. Hormonal proteins such as insulin, oxytocin and somatotropin coordinate bodily activities like glucose metabolism, childbirth contractions and protein production in muscle cells. Ovalbumin and casein are examples of proteins that store amino acids.