It's a mechanism that they have evolved in order to prevent foreign genes from entering a cell and being expressed.

它们进化出这种机制来,防止异源基因进入细胞并表达

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Taking foreign genes, genes that aren't naturally expressed or might not even exist inside a cell and putting them there and putting them there in a way where they work, and by work meaning the gene gets expressed or translated into a protein.

将异源基因,即那些在细胞中原本不表达或者,根本不存在的基因转入细胞并让它们工作,工作就是指让基因持续表达并合成蛋白质

耶鲁公开课 - 生物医学工程探索课程节选