Amino acids are the building blocks of the body that make up proteins. Protein substances are made up of twenty amino acids that form muscles, organs, glands, tendons, nails and hair. On the other hand, amino acids are classified into two groups; these groups are essential and nonessential amino acids. Amino acids obtained from food are called essential amino acids, while amino acids that our body produces from other sources are called nonessential amino acids. Also the key elements of an amino acid are oxygen, nitrogen, carbon and hydrogen. The growth and repair of all cells depend on them. An amino acid is an organic molecule with a basic amino group and a carboxyl group. Proteins are polymers of amino acids. Like lipids and polysaccharides, proteins are formed as a result of dehydration synthesis. The nitrogen of the amino group of one amino acid is bonded to the carbon group of another amino acid with a single covalent bond and the water is released. Through dehydration synthesis, amino acids are able to bond together to form polypeptides. For dehydration synthesis to occur, the carboxyl group of one amino acid must be adjacent to another amino acid group. Then, when they are adjacent, an enzyme can bring them together by catalyzing dehydration synthesis. ("Amino Acid")Furthermore, essential amino acids are those that cannot be synthesized by the body and must be consumed to obtain proteins from rich foods that contain them. Our body breaks down proteins to obtain essential amino acids and form new proteins. The essential amino acid can be found in eggs, dairy products, seafood and beans. Of the twenty amino acids present in our body, nine are essential in our diet. The nine essential amino acids that we can produce are lysine (one of... half of the paper... many tissues in the body), glutamine (which nourishes the brain and is mainly involved in the brain's utilization of glucose) and glutamate (our body uses it for the synthesis of proteins, for example for energy transport). (“Amino acids.”) In conclusion, amino acids are organic compounds that combine to form proteins. Amino acids and proteins are the building blocks of life. Amino acids are divided into two categories: essential and non-essential. Essential amino acids cannot be produced in the body. Accordingly, they must come from food. Nonessential means that our body produces amino acids, even if we don't get them from the food we eat. We believe that we need amino acids to survive because they make up about 75% of the human body and are also vital for every part of human function. Finally, amino acids can be used as a source of energy by the body.