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But if there were nothing beyond the DNA in cells, life could not exist.
VOA: special.2009.12.08
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It operates in a similar fashion to DNA polymerase in that it denatures locally or opens up the double stranded DNA, but it's different in that it creates a new polymer from the DNA template in the language of RNA, using RNA nucleotides and not DNA nucleotides.
它的作用机制类似于DNA聚合酶,在局部使DNA双链变性,解旋,但不同的是,它合成了一个基于DNA模板的,使用RNA编码语言的新聚合物,即使用核糖核苷而非脱氧核糖核苷
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Here the unique thing was that there's a restriction site inside that is present in normal DNA and not present in sickle DNA.
刚才例子中,特性就是在正常的基因中,有酶切位点,而在患者的基因中却没有
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It's also not using any sort of radiation, (which could destroy DNA remnants of the mummies.) "And finally, by using this Terahertz imaging, you eventually may be able to look at the substances within the mummy,for example, the embalming liquid used in the Egyptian way of embalming.
VOA: standard.2010.05.05
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They integrate their DNA into the host genome and you might not want to make that kind of a change in the cell.
而且也许你也并不想让逆转录病毒基因,整合进宿主的基因组
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Now in this case the host - you want the host not only to replicate all the DNA, you want it also to express the gene.
而这种情况下宿主--,你不只希望宿主复制基因,同时也想使之表达基因
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I talked about just not using viruses but using plasmid DNA together with lipids and that's another strategy for gene therapy.
这一部分我们不仅讲了病毒的应用,也讲了利用脂质体包裹的质粒DNA,基因治疗还有其它的策略
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You're not just trying to clone the DNA, you're trying to also clone or make many copies of the protein.
你不仅想要复制DNA,更想要克隆或是制造,许许多多的蛋白质产物
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Now DNA that's produced this way is not called genomic DNA because this doesn't match the DNA in your genome, on your chromosomes,right?
现在造出来的这个DNA,不叫基因组DNA,因为这跟你基因组里的DNA不一样,跟你染色体上的基因不一样,对吧
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The end result of transcription is not double stranded DNA, it's single stranded RNA where the RNA that's produced is called messenger RNA.
最终的转录产物并非双链的DNA,而是单链的RNA,称为信使RNA
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They're not whole genomes, but they're some small piece of DNA maybe the size of a protein.
不是整个基因组,而是小的DNA片段,但也许与蛋白质分子一样大
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It's not as simple as DNA going to RNA going to protein, because proteins need to be present in order to make these things happen as well.
基因表达不是简单的从DNA到RNA,再到蛋白质,因为整个过程需要,不同酶的催化作用
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So the DNA is going to get spread out on this gel according to size, with the small ones going farther and the large ones not going as far.
因此DNA会根据大小,在凝胶上分散开,小的片段会快一些,大的片段不那么快
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We want not only for the cell to be able to synthesize the DNA, you want it to be able to express the protein off the DNA as well.
我们不仅希望细胞能复制DNA,还希望它能表达目标DNA所编码的蛋白
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Well, it's not the DNA; they all have the same DNA.
不是DNA,它们的DNA都相同
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So the access that a cell has to certain kinds of genes, or chemical modifications of DNA, not chemical modifications that change the base pairs, that would be a mutation.
因此细胞变化的途径应该是对某些基因,或者DNA进行化学修饰,不是更改碱基对,更改碱基对就是突变了
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Then we'll talk about engineering of DNA and why this has been such - not only a rapidly growing and advancing area but one that's so important for Biomedical Engineering.
然后我们会谈论DNA工程,以及为何它不仅,是一个向前飞速发展的领域,而且对生物医学工程十分的重要
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The corresponding half of the ladder that corresponds to any given ladder, let's say the black DNA molecule that corresponds to the blue one is not just a mirror image.
与任何单链配对的,另一条单链,比方说与蓝色DNA分子,配对的黑色DNA分子,并不是蓝色DNA分子的镜像
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In fact, even if you haven't had a biology class it's hard to be alive in 2008 and not know something about DNA; it's become such an important part of our lives.
实际上,即使你们没有上过生物课,也不可能活在当下却对DNA一无所知,它已经与我们的生活密不可分
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One of the forms of processing that happens, that's very important in human gene expression is that some of the sections of the DNA molecule are not really necessary for describing the protein.
在人类的基因表达中,有一种非常重要的加工形式,那就是在DNA分子中有一些片段,对于编码蛋白质而言毫无用处
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Some of them are changes in the - not the sequence of DNA, not the sequence of nucleotides in the DNA but the chemistry of DNA around that the way that it's packed into a nucleus.
某些改变不是发生在DNA序列上,不是在DNA的核苷酸序列上,而是发生在DNA包装进细胞核的,一系列化学变化中
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Here's another picture of it here, showing it in a little bit more detail, that you have lots of DNA in each of the cells in your body but you're not using all that DNA at any one time.
这里有一张更加详细的图片,来说明这一点,人体内每个细胞中都含有大量DNA,但并不是所有的DNA都会同时发挥作用
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Now the challenge is not just to get the DNA that encodes a gene into a cell, the challenge is to get it into the cell in a form where the cell can use it, can express it and make proteins from it.
现在的问题不仅在于,要将编码基因的DNA转进细胞,还要让它进入细胞之后,能够为细胞所用,能够表达并合成蛋白质
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What I'm going to do is focus on a couple basic things that turn out to be really important for general applications, and then I'll talk not in too much detail about a few applications of DNA that you're probably familiar with to try to give you a framework to hang this on.
我要重点讲一些基础知识,这些知识在一般应用中十分重要,然后我会简略的讲讲,关于DNA的一些应用,你们可能已经比较熟悉了,我只是试着给你们打一个框架
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