which genes it is expressing at any one time and which ones are not expressed.

哪些基因不表达的机理十分复杂
I showed you this in this picture here and

我把这些都给你们显示在这张图上
those levels of control can be at the level of transcription.

调控可以在转录的水平下进行
There are molecules in cells

在细胞中有些分子能够
that give the DNA the signal that

给DNA发出信号告诉它
it's time to transcribe and express a gene,

是时候转录和表达某基因了
those are called transcription factors,

这些分子叫做转录因子
we'll talk about them a bit later.

晚些时候我们会讲它们
There's interfering with RNA processing,

有一种机制能够干扰RNA加工过程
and I'm going to talk about that in the next couple of slides

我会在下面几张幻灯片里讲到
because there's a couple of new methods for -

因为有一些新方法能够--
or potentially interfering with gene expression in living animals

潜在地干扰活体动物体内基因的表达