They're not whole genomes, but they're some small piece of DNA maybe the size of a protein.

不是整个基因组,而是小的DNA片段,但也许与蛋白质分子一样大

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So the DNA is going to get spread out on this gel according to size, with the small ones going farther and the large ones not going as far.

因此DNA会根据大小,在凝胶上分散开,小的片段会快一些,大的片段不那么快

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