Amino acid reference chart contains the twenty amino acids found in eukaryotes, grouped according to their side chains and charge. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Start studying 20 Standard Amino Acids. Other sections include matter, elements, the periodic table, reactions, and atoms. The Twenty Amino Acids The twenty amino acids (that make up proteins)each have assigned to them both three-letter (can be upper or lower case) and one-letter codes (upper case). Amino acids are organic compounds composed of nitrogen, carbon, hydrogen and oxygen, along with a variable side chain group. Adults need nine essential amino acids that … Chem4Kids.com! This tutorial introduces amino acid structure. Learn about these 20 amino acids. For example, based on the propensity of the side chain to be in contact with water, amino acids can be classified as hydrophobic (low propensity to be in contact with water), polar and charged (energetically favorable contact with water). Roughly 500 amino acids have been identified in nature, but just 20 amino acids make up the proteins found in the human body. This makes it quicker and easier for notation purposes and are worth learning. The 20 amino acids and their main functions 1- Phenylalanine Phenylalanine is an amino acid found in three forms: L-phenylalanine (naturally synthesized), D-phenylalanine (artificially synthesized) and DL-phenylalanine (a mixture of the two above). Twenty Amino Acids There are twenty amino acids required for human life to exist. Each of the 20 most common amino acids has its specific chemical characteristics and its unique role in protein structure and function.