These are molecules that exist naturally in cell membranes and are activated by certain enzymes and kinases generated by receptors.

这些分子存在于细胞膜表面,能被受体激活的某种酶或激酶所活化

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It can't enter cells because it's too big and it's too water soluble so it can't go through cell membranes.

它的分子太大了所以无法进入细胞,而且还是水溶性的,所以它也无法穿过细胞膜

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So most of the lipids, which make up cell membranes in your body are of this category of phospholipids.

大部分脂类,那些在你体内构成细胞膜的脂类,都属于磷脂类

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Many of them are derived from cholesterol and they're hydrophobic, which means they can penetrate through cell membranes.

多数分子都来自于胆固醇,它们是疏水性的,这意味着它们能够穿过细胞膜

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There's lipid chains in between so cell membranes are lipid rich layers that can exist in water.

脂质链在两者中间,所以细胞膜是富含脂类的膜层,并可以稳定存在于水中

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If a cell membrane was indeed just a lipid bilayer, then glucose could never enter the cell because it can't permeate through cell membranes.

如果细胞膜只是一个脂质双分子层的话,葡萄糖就不可能进入细胞,因为它不能渗透过细胞膜

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All cell membranes have these channels within them, and under their resting conditions sodium is moving from outside to inside, potassium's moving from inside to outside.

所有细胞膜上都有这种通道结构,在静息状态下,钠从细胞外流向细胞内,钾从细胞内流向细胞外

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Now that's not the only thing in cell membranes, there are also proteins in cell membranes, and these proteins are special proteins that can exist within membranes like this, and they exist because these proteins also have different segments with different properties.

但细胞膜并不只由磷脂构成,细胞膜里还有蛋白质,而且这些蛋白质是一些,可以在细胞膜中存在的特殊的蛋白质,而这些蛋白质存在于细胞膜中,源于它们也有溶解性不同的片段

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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

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