蛋白质是一类极为重要的大分子，几乎各种生命活动无不与蛋白质的存在有关。

蛋白质是一类极为重要的大分子，几乎各种生命活动无不与蛋白质的存在有关。 氨基酸是蛋白质的基本组成单位。人体内蛋白质的种类很多，性质、功能各异，但都是由20种氨基酸（Amino acid）按不同比例组合而成的，并在体内不断进行代谢与更新。<br> 蛋白质又分为完全蛋白质和不完全蛋白质。缺乏必需氨基酸或者含量很少的蛋白质称不完全蛋白质，如谷、麦类、玉米所含的蛋白质和动物皮骨中的明胶等。

Protein is a kind of very important macromolecules. Almost all kinds of life activities are related to the existence of protein. Amino acids are the basic components of proteins. There are many kinds of proteins in the human body with different properties and functions, but they are all composed of 20 amino acids in different proportions, which are constantly metabolized and updated in the body.<br>Proteins are divided into complete proteins and incomplete proteins. Proteins lacking essential amino acids or with little content are called incomplete proteins, such as proteins contained in grains, wheat and corn and gelatin in animal skins and bones.

Protein is an extremely important macromolecule, and almost all kinds of life activities are related to the existence of protein. It is the basic unit of amino acid protein. There are many kinds of protein in human body with different properties and functions, but they are all composed of 20 kinds of Amino acid in different proportions, and they are constantly metabolized and renewed in the body. Protein is divided into complete protein and incomplete protein. Protein, which lacks essential amino acids or has little content, is called incomplete protein, such as protein contained in grains, wheat and corn, gelatin in animal skins and bones, etc.