Muscles are built from protein. We need to consume enough protein to allow our muscles to be healthy and perform work.
Generally, to survive we consume only several types of biological molecules: carbohydrates, lipids, and proteins (plus vitamins and the "non-biological" molecules: minerals and water)
The proteins are made up of smaller molecules called amino acids.
Biologically active proteins are polymers of consisting of amino linked by covalent peptide bonds.
Once consumed, a protein is digested into the smaller amino acids and transported to the all the cells of the body where the amino acids can be put back together to make the proteins the body needs.
Amino acids enter onto the general metabolic pathways which have been called anabolism and catabolism.
Most proteins the body makes function as structural proteins. Muscle tissues and connective tissues are mainly composed of proteins.
Some proteins have an extremely important function by serving as enzymes. Enzymes make biological chemistry efficient and less wasteful of energy. Still there are other "jobs" for proteins.
They can be involved in the immune response. Mechanism and serve as carrier or transport molecules and also participate in the translation of DNA.
A specific group of body’s proteins specializes in moving nutrients and other molecules into and out of cells. Some of these transport proteins act as pumps, picking up compounds on one side of the membrane and depositing them on the other.
Obviously, the new born animal needs lots of proteins for growth and maturation. The genes of DNA decide which amino acids (obtained from digestion) will go on to make a protein the cell needs for whatever structure or function requirement.
Some twenty two or more different amino acids are needed for the growth of new tissues, for the maintenance of established cellular constituents and for other metabolic requirements.
So it is remarkable that some proteins work together (with DNA/RNA) to make more proteins. Proteins, it might be said, more than any other molecule, are good at "re-booting" themselves.
Regarding the other nutrients taken with protein, apart from fat and carbohydrate it must also be accompanied by the full array of vitamins and minerals.
Other factor, protein quality, helps determine how well a diet supports the growth of children and the health of adults. Two factors influence protein quality; a protein’s digestibility and its amino composition.
Protein in Human Nutrition
