| environ. |
amino acid Organic compounds containing a carboxyl group (-COOH) and an amino group (-NH2). About 30 amino acids are known. They are fundamental constituents of living matter because protein molecules are made up of many amino acid molecules combined together. Amino acids are synthesized by green plants and some bacteria, but some (arginine, histidine, lysine. threonine, methionine, isoleucine, leucine, valine, phenylalanine, tryptophane) cannot be synthesized by animals and therefore are essential constituents of their diet. Proteins from specific plants may lack certain amino acids, so a vegetarian diet must include a wide range of plant products (含有羟酸基(-COOH)和氨基(-NH2)的有机化合物。已知的氨基酸约有30种。蛋白质分子是由许多氨基酸分子所结合，因此，氨基酸是生物的基本构成物质。氨基酸由绿色植物和一些细菌合成，但也有一些氨基酸(如精氨酸、组氨酸、赖氨酸、苏氨酸、蛋氨酸、异亮氨酸、亮氨酸、缬氨酸、苯基丙氨酸和色氨酸)是动物本身无法合成的。因此，这些氨基酸是动物饮食中的重要成分。某些植物蛋白可能缺乏某些氨基酸，因此，素食者应食用各种各样的植物产品。) |
