This cell can only be an effective barrier if there's no way to get past it.

这些细胞只有密不透风,才足以形成一道屏障

耶鲁公开课 - 生物医学工程探索课程节选

The problem it solves for the cell is how to do I make a barrier around myself to define what's in me and what's outside of me when most of what's around me and what's in me is water.

它为细胞解决的问题是,当我体外和体内大部分都是水情况下,我怎样在自己周围设置一个界线,来区分什么是体内的,什么是体外的

耶鲁公开课 - 生物医学工程探索课程节选

These junctions, these red dots here are actually made up of proteins, some are synthesized by one cell, some are synthesized by each other, and they lock together to form a very tight barrier, to form a tight junction between the two cells.

这些红点表示细胞连接,实际上是由蛋白质构成的,有些是由一个细胞单独生成的,有些是由两个细胞共同生成,使这两个细胞紧锁在一起形成紧密的屏障,并在两细胞间形成紧密连接

耶鲁公开课 - 生物医学工程探索课程节选

We talked about this a little bit in section last week, when you eat vegetables or meat, you're eating a lot of DNA but that doesn't enter the cells of your body because of the barrier properties of cell membranes.

这个我们上周讨论会讲过一些,我们在吃蔬菜或者肉类时,摄入了大量DNA,它们之所以不会进入你的体细胞,就是由于细胞膜的这种屏障作用

耶鲁公开课 - 生物医学工程探索课程节选