There are more than 20 amino acids that make up the biological polymers called proteins, so there are 20 choices of each amino acid at a position on a protein.

而那些称为蛋白质的生物活性多聚体,是由二十种不同氨基酸所构成,因此每个蛋白质的,任意位点都有多达二十种氨基酸可供选择

耶鲁公开课 - 生物医学工程探索课程节选

We're familiar with polymers, plastics in our daily life; the chairs that you're sitting on are made of a kind of a plastic polymer that is basically an organic chemical that is cross-linked together.

我们应该很熟悉聚合物,比如日常生活中的塑料就是,你们坐的椅子,就是由一种塑料聚合物构成,它由基本的有机化学物质交联在一起

耶鲁公开课 - 生物医学工程探索课程节选