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蛋白质的种类很多,各种不同的蛋白质分子都是由多种不同的氨基酸以不同的数量各按一定的排列次序构成。人吃了食物,其中的蛋白质先被消化成氨基酸,然后。氨基酸被吸收、运送到身体各个部分,再按照本身蛋白质分子的构造组成新的蛋白质。人体蛋白质由二十多种氨基酸组成。其中有十多种氨基酸,人体能自行合成或转化而成。但另有八种氨基酸,必须依靠食物直接供应。这八种氨基酸就称做人体必需的氨基酸,它们是:赖氨酸、蛋氨酸、色氨酸、苏氨酸、亮氨酸、异亮氨酸、缬氨酸、苯丙氨酸。人体蛋白质是由这二十多种氨基酸以一定的比例组
There are many kinds of proteins, and various protein molecules are composed of different amino acids in different numbers in a certain order. People eat foods, in which proteins are first digested into amino acids, and then. Amino acids are absorbed and transported to various parts of the body, and new proteins are formed according to the structure of their own protein molecules. Human proteins consist of more than twenty amino acids. Among them, there are more than 10 kinds of amino acids that can be synthesized or transformed by the human body. But there are eight other amino acids that must be supplied directly from food. These eight amino acids are called essential amino acids. They are: lysine, methionine, tryptophan, threonine, leucine, isoleucine, valine, and phenylalanine. Human proteins are composed of these twenty amino acids in a certain proportion