第十四章 蛋白质和核酸（The fourteenth chapter protein and nucleic acid）.doc

第十四章 蛋白质和核酸（The fourteenth chapter protein and nucleic acid） The fourteenth chapter: protein and nucleic acid Section 1 - amino acids The existence, classification and nomenclature of alpha amino acids Amino acid is the hydrogen atom of the carboxylic acid molecule is alkyl amino (-NH2) substituted derivatives, is the basic unit of protein. Natural amino acid is found in about 200 kinds of protein amino acids constitute about 30 species, of which there are more than 20 kinds of common people, these amino acids called protein amino acids. No other amino acids involved in proteins known as non protein amino acids. In addition to proline, more than 20 kinds of common amino acids are alpha amino acids, and their structures can be expressed by general formula: Alpha amino acid can be divided into aliphatic alkyl amino acids, aromatic amino acids and heterocyclic amino acids; according to molecular amino (-NH2) and carboxyl (-COOH) the number of different amino acids can also be divided into neutral amino acids (equal to the number of carboxyl and amino), acidic amino acids (amino carboxyl number is greater than the number of basic amino acids (amino), more than the number of carboxyl groups). Amino acids are usually named by the name according to their origin or nature, such as amino acid with sweet called glycine, serine from the earliest silk named. In use for the sake of convenience, the commonly used English name abbreviations and symbols (usually three letters) or Chinese code. For example Gly or G or glycine Gan word to denote its name. Amino acid nomenclature and other substituted carboxylic acids with the same name, the parent carboxylic acid as the name. Amino acids that make up proteins, There are eight kinds of animals that are unable to synthesize themselves and must be obtained from food. They cause disease when they are deficient. They are called essential amino acids. The amino acids that make up proteins are found in table P177 14-1 Two. Structure and pro