There are an estimated 100,000 different proteins in the human body alone, and each of them is made up of a combination of different combinations of only 20 amino acids . Each protein has a different structure and performs a different function in the body. When we eat protein-containing foods (such as meat, fish, beans, eggs, cheese, etc.) the polypeptide chains are generally broken down in the digestive tract and the individual amino acids are absorbed into our bodies. These amino acids are then recombined into proteins specific to each individual person in a process called protein synthesis .
Lipids that contain a functional group ester are hydrolysable in water. These include neutral fats, waxes, phospholipids, and glycolipids.
Nonhydrolyzable lipids lack such functional groups and include steroids and fat-soluble vitamins (. A, D, E, and K). Fats and oils are composed of triacylglycerols or triglycerides. These are composed of glycerol (1,2,3-trihydroxypropane) and 3 fatty acids to form a triester. Triglycerides are found in blood tests. Complete hydrolysis of triacylglycerols yields three fatty acids and a glycerol molecule.