 peptide bond formation. Let's examine the biochemistry behind the formation of peptide bonds. Inside cells, peptide bonds are formed within ribosomes during a process called translation. Peptide bonds are the building blocks of proteins. Proteins are polypeptides that are folded into specific three-dimensional structures. Polypeptides are composed of amino acids covalently bonded to each other like beads on a string. The covalent bond that holds amino acids together is called a peptide bond. All 20 amino acids share a common structure that includes a central alpha carbon covalently bonded to a carboxyl group and a mean group, a hydrogen, a variable R group. Study the amino acids below. Can you identify the central alpha carbons? Can you identify the carboxyl groups? Can you identify the amine groups? Can you identify the variable R groups? During protein synthesis or translation, amino acids are covalently bonded to each other through a peptide bond. This reaction, which takes place within ribosomes, is known as a dehydration synthesis reaction. Dehydration synthesis reactions are commonly used in cells for anabolic or synthesis reactions. Watch this formation of a peptide bond between two amino acids. An OH is removed from the carboxyl group of the amino acids on the left. An H is removed from the amine group on the right. An OH and an H form water H2O. This is dehydration because water has been lost. A covalent bond can now form between the amino acids. This is a peptide bond. You have completed this activity, peptide bond formation.