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They go across the membrane - this is the trans-membrane part of the receptor that's going across the membrane.
它们跨越式的存在于细胞膜上,这就是受体的跨膜部分,它跨越了细胞膜
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I mentioned earlier, we thought about receptors as being these blocks and membranes but there are different families of receptors.
我之前讲过,我们把受体看做一类,固定在细胞膜上的分子,但受体有许多不同家族
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Essentially, what they are is it's a protein that spans the membrane of a cell.
本质上来说，它是一个横跨细胞膜的蛋白质。
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s a single cell layer of a damage cochlea.
损伤后的耳蜗只有一层薄薄的细胞膜，There’
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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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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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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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That general class of molecules is called receptors and its shown here just as a block of material living in the cell membrane.
这一类分子叫做受体,在这里看起来就像是,生活在细胞膜内的物质
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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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Now, sodium and potassium don't ordinarily move across membranes, they're charged molecules, they can't dissolve, they can't permeate through a cell membrane, but they go through because there are channels that allow them to pass through in the membrane.
钠和钾通常是不能跨过细胞膜的,它们都是带电粒子,它们不能溶解在细胞膜中,不能渗透通过细胞膜,但它们之所以能通过细胞膜,全赖膜上离子通道的作用
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On the side over here shows a cell membrane and so this is outside the cell above it, and this is inside the cell below, and this is the lipid bilayer that separates the outside of the cell from the inside of the cell.
这边这个表示细胞膜,它的上面代表细胞外部,下面代表细胞内部,这个是脂质双分子层,将细胞内外分开
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This is a picture of patch clamp, it's a device that engineers built to fasten onto individual cells in order to look at how molecules in the membrane of the cell are working, and I'll talk a little bit about that as we go along.
这是膜片钳的图片,工程师使用该装置固定单个细胞,由此观察,细胞膜中的分子怎样活动,在以后的课中我还会谈到这方面内容
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They carry a potential, that is, if you could - if you had a tiny, tiny electrical meter, you could one put one electrode on one side of the cell membrane, on the extracellular side and one on the intracellular side and measure, you would measure a potential difference; just like a battery you would measure a potential difference.
它们带有电势,就是说,如果你能有一个足够小的电位计,可以把一个电极放在细胞膜一侧,假设放在细胞外的一侧,另一个电极放在细胞内侧并测量,你能测到一个电势差,就像电池那样能测到电势差
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So, for example, if we look at sodium channels, and sodium channels are some of the particularly prevalent ones when we're talking about neurons, if you think about the cell membrane, and this little green cartoon is me trying to show a sodium channel here, and in this case, you can see that it's closed, such that no ions are getting through.
比如，让我们来看一下钠离子通道，钠离子通道是我们会经常遇到的几个之一,在讨论神经元的时候，如果大家想想细胞膜，而这个绿色的小示意图就是我用来表示,钠离子通道的，在这种情况下，大家可以看到它是关闭的，因此没有离子可以通过。
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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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It has to be small, and it has to be lipid soluble in order for it to pass through a cell membrane.
这些分子必须非常小,而且必须是脂溶性的,才能穿过细胞膜
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There are - that's one class of proteins on the surface I'm sorry.
对不起,这是细胞膜蛋白的一个种类
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It turns out that one of the places that's been very fruitful to look for proteins that differ between cell populations is on the surface of the cell.
而事实证明,寻找能鉴别细胞种类的,特定蛋白的最佳位置,是在富含蛋白的细胞膜上
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Because of that they're barriers, they separate the inside of the cell from the outside of a cell, and only certain kinds of molecules can pass through a cell membrane.
因为它们的屏障作用,将细胞内外区隔开来,只有特定的,某些分子才能穿过细胞膜
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Because these molecules can span across the membrane from outside to inside, they're in just the right position to take messages that they receive from outside the cell and transmit them through the membrane into the cells internal apparatus, and that's what they do.
因为这些分子能穿过细胞膜,连通细胞内外,它们所在的位置非常适于接受信息,它们能将外界获得的信息,通过细胞膜传递给细胞器,这正是它们的功能
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They have a nucleus, they have a cell membrane, they have organelles throughout them, they have the same DNA.
它们都有细胞核,细胞膜,细胞器遍布其中,它们有相同的DNA
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I do want to talk about one important subject which you might not have thought too much about and that's lipids, because lipids are so important to the structure of the body because they make up the membranes that form the cells that are the fundamental units.
我的确想要讨论一个重要的主题,这个主题也许你们都没有深入思考过,那就是关于脂类的问题,脂类对身体结构形成十分重要,它是组成细胞膜的基本单位,而细胞膜能够维持细胞形态
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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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Insulin, the ligand binds to its receptor, creates a change through a kinase activity that's exposed, which leads to other biochemical changes, which leads to a change in cell behavior - in this case the cell behavior is that more glucose transporters are brought to the membrane and more glucose can enter the cell.
胰岛素,一种能够与受体结合的配体,通过其暴露出的激酶活性引起的变化,导致了其它后续生化变化的发生,进而使细胞行为发生改变,这个例子中的细胞行为就是,更多的糖载体被带到细胞膜表面,这样更多的糖分子进入到细胞内部
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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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That RNA is made into proteins, and proteins are the working molecules of the cell, they're enzymes, they're structural molecules, they're are proteins that exist in the membrane that allow things to go in and out of the cell, so really the working molecules are the cell in every sense.
这些RNA指导合成蛋白质,蛋白质是细胞生命活动的承担者,它们可以是酶,或是结构性分子,也可以存在于细胞膜上的膜蛋白,能够让一些物质通过它们进出于细胞,所以蛋白质才是真正意义上,细胞生命活动的承担者
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