There's just more sequences in a three unit codon than I need for the amino acids.

一个氨基酸对应不止一个密码子,由三碱基所构成的密码子

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So the repeating unit in DNA is this structure here, a nucleotide, which has three different regions.

NA的重复单位就是,核苷酸,它有三个不同的区域

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