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Remember that these cells are relatively large compared to bacteria and so diffusion doesn't occur very quickly over this length scale.
要知道这些细胞相对细菌而言,还是比较大的,扩散作用在这种尺度上,发生得不是那么快
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So, you're familiar with some of these bacteria like salmonella, or the micro bacterium that causes tuberculosis are shown here.
所以 你们很熟悉像沙门氏菌这样的细菌,或者像这儿的引起结核的小细菌
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You sneeze because you've got all these germs inside you and your body wants to get the germs out, so you sneeze.
你打喷嚏，因为细菌在你体内,你的身体想把他们赶出去，所以你打喷嚏。
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So look, why am I justified in believing in germs, various kinds of viruses that I can't see, or bacteria or what have you, that I can't see?
所以,我为什么相信微生物,相信各种肉眼无法看到的病毒,细菌等诸如此类我看不到的东西确实存在
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If you're a bacterium your whole life is about swimming to nutrients and running away from things that would kill you.
假如你是一个细菌,你的一生将会在追逐养分,和逃避敌害中度过
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Movement down a concentration gradient occurs fairly rapidly over short distances like a micron or so, like the size of a bacterium.
顺浓度梯度扩散在一微米左右的短距离内,相当迅速,一微米相当于一个细菌的大小
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The bacterium doesn't have a nucleus, and in fact, they don't have very well formed organelles in general.
细菌没有细胞核,实际上,细菌没有完善的细胞器
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So, I have a bacteria infection, stimulates my immune system, I start making antibodies that bind to an antigen specific to that bacteria.
所以 如果我被细菌感染了,我的免疫系统被激活,开始制造抗体,这些抗体结合到细菌特异性的抗原上
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The study of immunology is the study of mechanisms that your body uses to protect itself from mainly from foreign pathogens like viruses and bacteria.
免疫学研究身体,采用何种机制来保护自身,免受外源病原体如病毒和细菌的伤害
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Hopefully each one of those cells is containing one or more of the plasmids that you're interested in and those are being copied as well.
如果顺利的话每个细菌里都含有,一个或更多我们所感兴趣的质粒,而它们也正在被复制
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From this person--this perspective, a person is just a germ's way of making other germs.
从这个角度看，这个人，人来只是细菌繁殖的方式。
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Won't help me against other bacteria, but only against the one that I've got.
但对其他细菌却不起作用,只能抵抗我感染到的这种细菌
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Why don't bacteria need a distinct nucleus and that's necessary in a human cell?
为什么细菌不需要单独的细胞核,而对人类细胞则为必需
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Well, you could think about the cell wall of a bacterium as its skeleton, it's what protects it from mechanical forces that are out in the world.
你可能认为细菌的细胞壁,就像骨骼一样,使其免受,外界机械力的伤害
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Antibiotics are chemicals, usually small organic molecules that will kill micro-organisms like bacteria.
抗生素是一类化学物质,它们通常是小分子有机物,能够杀死细菌这样的微生物
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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 you could use sort of negative selection in order to find the ones that you want.
这样你就可以用某种负向选择,去找到你想要的细菌
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If your gene goes in, you've interrupted the gene for antibiotic resistance and those new organisms aren't going to be resistant to antibiotic anymore.
如果基因进入了质粒,原本对抗生素有抗性的基因就被打断了,那些新细菌就不再对抗生素有抗性
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This is a bacterium that's normally present in humans; it colonizes all of our intestinal systems.
这种细菌在人体中很常见,栖居在我们所有人的肠道系统中
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In this particular example here we're exposing these plasmids to bacterial cells.
我举一个特别的例子,我们把这些质粒暴露给细菌
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if you do that under the situation where you've put your plasmid into these micro-organisms then you're going to have little colonies that grow many copies of the bacterial cells.
如果你在质粒已经进入了微生物,的情况下培养它们,你就会得到许多小菌落,里面长有很多增殖出来的细菌
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your innate immune system tries to get rid of them.
你的先天性免疫系统试着去清除细菌
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That's another difference between human cells and bacteria.
这是人类细胞和细菌的另一个不同
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That's a way of culturing or propagating bacteria.
这是培养繁殖细菌的一种方式
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We'll learn more about that in a moment, but basically it allows the immune system to distinguish between viral and bacterial pathogens, and respond appropriately depending on the type of pathogen that's there.
我们一会儿会学到不少,但基本上说,这样一来免疫系统,就能够分辨出病毒和细菌病原体,并对相应的病原体类型,产生合适的免疫反应
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Now that's going to be important when we talk about making human gene - making human proteins inside alternate hosts like bacteria, that they can't do all the things that your cells can do.
这一步骤在我们谈到,利用像细菌那样的宿主,来生成人类蛋白时非常重要,因为细菌并不具备人类细胞的全部功能
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There are different kinds of cell walls in bacteria but they have a rigid cell wall and our cells don't have a rigid cell wall, we have a fluid lipid like cell wall.
细菌有不同种类的细胞壁,但都很坚固,人类细胞没有坚固的细胞壁,我们有一层类似细胞壁的流动的脂类
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I'm not going to talk about them in detail but please look at that to remind yourself of those kinds of specialized sub-cellular units which are present in cells in humans but not present in bacteria.
我就不再赘述了,不过请你们看看书,回忆一下哪些特化的亚细胞结构单元,是人类细胞有,而细菌没有的
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You've probably seen agar plates, if you smear a solution that's contaminated with bacteria on it, then that bacteria will grow on this agar rich medium and you'll get many, many copies of the bacteria that you've smeared at low density onto the plate.
你们大概见过琼脂培养基,如果将有细菌的溶液涂抹在培养基上,细菌就会在富含琼脂的培养基上生长,你会得到许多许多细菌,即使你只涂抹了低浓度溶液
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In fact, that's their preferred state is suspended in a fluid where nutrients are widely available to them, and where they can swim from one spot to another in order to get the nutrients they need, or in order to run away from toxic compounds.
事实上,细菌更喜欢生活在,营养丰富易得的悬浮液中,它们可以从一个点游动到另一点,以获取所需营养,或逃离有毒物质
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