The major reason of variation is change in DNA level.

变异的主要原因是DNA发生改变。

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Epigenetics commonly refers to the developmental process by which cellular traits are established and inherited without a change in DNA sequence.

表观遗传学通常意指通过表观遗传学，细胞特征被建立并且遗传，而在DNA序列上没有改变的发育过程。

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Things written in pen you can't change. That's DNA. But things written in pencil you can.

用钢笔写下来的东西是无法改变的。这是 DNA。但是用铅笔写下来的东西是可以改变的。

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They integrate their DNA into the host genome and you might not want to make that kind of a change in the cell.

而且也许你也并不想让逆转录病毒基因,整合进宿主的基因组

耶鲁公开课 - 生物医学工程探索课程节选

However, a small percentage of people are born with a single-letter change in their DNA for this enzyme that causes the codeine-to-morphine reaction go faster.

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He added that 162, 000 DNA samples had been retained following the change in the law.

BBC: Rules covering the handling of DNA samples changed in 2001

That started to change in 1976, with the founding of Genentech (nyse: DNA - news - people ), the first biotechnology company.

FORBES: Magazine Article