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What was neat about it is before that time, the predominant species to use for air conditioning or refrigeration was ammonia.
在这之前是很整洁的，之前最主要的用于空调或者冰箱的,物质是氨。
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And, not too many people, actually, if you talk to your grandmother or grandfather, there were some refrigerators that were actually made that used ammonia.
但是，并非太多的人，如果你会对你的祖父，祖母谈谈，或许有一些冰箱,实际上是用氨。
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One way is to allow these bacteria to grow on a plate that is loaded with antibiotics like Ampicillin.
一种方法,是让这些细菌,在有大量抗生素如氨苄青霉素,的培养基上生长
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So what we see is on ammonia here, 107 we know that it's less than a 109 . 5, it's actually 107, so it's less than a 109 . 5, because of that lone pair pushing down in the bonding electrons.
我们看到在氨分子里，我们知道它比１０９．５要小，它是，所以比109。5要小，因为孤对会把成键电子向下推。
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We're going to use that Ampicillin resistance in technological ways and I'll describe that in a minute.
我们将通过技术手段,利用这种氨苄青霉素抗性,马上我就会讲到
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If this plate has Ampicillin in it, then the only cells that would be able to grow here are cells that have resistance to Ampicillin.
如果培养基上有氨苄青霉素,那么能在这里生长的,只有那些对氨苄青霉素有抗性的细胞
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And what is the shape, for one more clicker question on ammonia?
那它的形状呢？,再来一道关于氨分子的课堂习题？
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This process of using a biological event like resistance to Ampicillin in order to pick out the cell population that you're interested in is called selection.
这个利用生物特性,如对氨苄青霉素的抗性,来挑出你所感兴趣的细胞的过程叫筛选
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If a cell has a gene that makes it resistant to Ampicillin, that means that that micro-organism can survive being exposed to this normally deadly chemical without dying.
如果细胞带有一种基因,能够让它对氨苄青霉素产生抗性,即使把它放在,有致死剂量化学物质的环境中,它也能存活下来
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So we can have our two hydrogen atoms come in here, and what we will find is - now that we have all of our orbitals filled up -- so thinking about what this angle is here, would you expect it to be less than or greater than what we saw for ammonia before?
我们在这里有两个氢原子，我们会发现,现在我们所有的轨道都填满了-,考虑一下这里的角度，你们觉得它比在氨中看到的,要大还是要小？
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If you selected the cells right than the only ones that have that resistance to Ampicillin are the ones that successfully got your plasmid and are using this Ampicillin resistant gene.
如果你选对了细胞,那么对氨苄青霉素有抗性的就是,成功得到了质粒并表达了基因的细胞
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Ampicillin is an antibiotic.
氨苄青霉素是一种抗生素
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You could imagine strategies where you have multiple resistance genes on a plasmid, resistance to Ampicillin, to Penicillin, to Erythromycin for example, and you design strategies for separating out which cells are carrying the plasmid that you're interested in.
若质粒上有多种抗性基因,你就有很多筛选方法,例如对氨苄青霉素,青霉素,红霉素的抗性,而且你可以设计方法分离出,含有你感兴趣质粒的细胞
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If we grew these cells on a plate loaded with Ampicillin and we could select cells that have Ampicillin resistance, and this process of selection and cell culture is very important and we'll talk about it more next week.
如果我们在含有氨苄青霉素的,培养基上培养细胞,我们可以筛选出,对氨苄青霉素有抗性的细胞,这个筛选和培养细胞的过程是很重要的,我们下星期会讲到这些
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The property it gives here is called AMPR or resistance to Ampicillin.
这里给出的这种特性叫做AMPR,即对氨苄青霉素的抗性
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So if we do this and we form the molecule ammonia, let's switch to a clicker question, and have you tell me what the bond angle - is going to be in ammonia -- HNH Actually, let me draw it on the board as you look -- actually, can you put the class notes on, since you don't actually have your notes to refer to.
如果这样做的话，我们就可以形成氨分子，让我们来做一个课堂练习,你们告诉我氨分子中的键角是多少-,键角，the，h，n，h，bond，angle。,实际上让我在黑板上画出它来，这样你们可以看到实际上-,你能把课堂讲义放出来吗，因为你们没有讲义可以参考。
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