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When it cuts it leaves sticky ends or un-base paired single stranded regions on each end of the part its cut and that's just a property of many restriction enzymes; not all, some cut blunt,just right down the middle.
它切割后会留下两个粘性末端,或者未配对的单链部分,这是许多限制性内切酶的特性,但不是全部,有些限制性内切酶是从中间钝切的
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Certain double stranded RNA sequences will cause in the cell a process of degradation of very specific RNA sequence.
一些双链RNA序列能够在细胞中开启,特定RNA序列的降解程序
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This is - what this diagram shows you is-- the forces that hold these individual strands of DNA into a double stranded form.
你们可以看看这个图表,演示了连接两条DNA长链为双螺旋,结构的化学力
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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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It doesn't cut straight across the double stranded DNA but it cuts in this jagged fashion.
它不直接横切双链DNA,而是留下一个锯齿形切口
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The DNA molecule here has been spread apart, opening up two single stranded DNA's which have complementary base sequences because they were double stranded DNA.
这里DNA分子被分开,形成两条单链DNA,这两条单链碱基序列互补,因为它们是由双链DNA解旋形成的
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The result of this process if this replication went down the whole length of the DNA would be to form two identical, double stranded DNA molecules.
如果复制过程在整条链上持续进行的话,将生成两条完全一样的,双链DNA分子
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It's a double stranded circular piece of DNA, meaning that the 3', 5'ends that hang off are joined back together again to form a continuous loop.
它是双链环状DNA,它的3'末端和5'末端首尾相连,构成一种连续环状结构
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Now, in your book, there's an example of plasmid where I've given you the exact sequence of nucleotides that makes up the whole double stranded DNA molecule.
现在在你们书里,有个质粒样本,我将组成这个双链DNA分子的,核苷酸序列写在这里了
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It's very important in the biological operation of human cells and that step is RNA splicing, or processing of this RNA, single stranded RNA that's produced by transcription.
而这对人类细胞生物运作至关重要,这个步骤就是RNA剪接,或者说是对RNA的加工,对转录出的单链RNA进行加工的步骤
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It has to do with the nature of this complementary binding between double stranded DNA and the fidelity of this base pair matching in forming stable DNA molecules.
这些特性能从根本上解释,为何DNA双链的碱基能互补配对,以及在形成稳定的DNA分子结构时,碱基互补配对为何具有一致性
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The end result is you can design now very specific double stranded RNA sequences, that when delivered into cells again will activate this process of natural degradation of an existing messenger RNA.
最终的结果是,你现在能够设计针对性很强的,双链RNA序列,当这段序列被转入细胞后会激活,对已有信使RNA进行降解的过程
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When it's double stranded this gene can't be translated, because you have to have the single strand in order for the transfer RNA to bind and for this process of translation to take place.
当基因处于双链结构状态时,是不能进行翻译的,因为必须把双链拆开得到单链,才能结合转运RNA并开始翻译过程
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Remember we talked about how DNA replicates itself and that there are enzymes, DNA polymerase that bind to the double stranded DNA, separate it, denature it locally, and then start the process of replication.
请记住DNA复制必须有酶的参与,DNA聚合酶结合在双链DNA上,打开双链并原位变性,然后才开始复制
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Well, what if you knew the sequence for the messenger RNA that made insulin and you designed another single stranded DNA or RNA molecule that was the exact opposite, or the exact compliment, I should say, of that strand?
那么,如果你知道了,合成胰岛素的mRNA的序列,并设计一段与其序列完全相反的,DNA或者RNA分子,应该说是完全互补的一段分子
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The first step is to take the DNA fragments that we're interested in and put them into this vector by basically cutting open the double stranded DNA and inserting the gene that we like in the region where we've cut.
第一步是把我们感兴趣的DNA片段,整合到这个载体里,基本的方法是切开质粒这个双链DNA,把我们想要的基因插入切开的区域
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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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The native structure is this double stranded structure here and if I heat it up slightly and I add some base, so under slightly basic conditions, these molecules will fall apart because you've created conditions where the hydrogen bonding is no longer favorable so they peel apart.
原始结构,在这里就是指DNA双链,如果我稍微加热,并且加入一些碱,在弱碱性的条件下,这些配对碱基会分开,这是因为在一定条件下,碱基对之间的氢键,不再稳定并且会断裂分开
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Now the nice thing about this is that the degradation mechanisms seem to persist for some period of time, beyond the time at which you deliver the double stranded RNA; whereas, obviously, this mechanism here is only going to exist for as long as the anti-sense sequence is present.
而好消息是降解过程会持续一段时间,比你转入双链RNA的时间要长,但是,这种机制只会在,有反义链的时候发挥作用
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If I had a beaker sitting on the table here and it contained a million blue double stranded DNA molecules and a million red double stranded DNA molecules and I heated it up and added a little base, I'd soon have four million individual strands just floating around in the solution because I've broken up this hydrogen bonding and the DNA molecules fall apart.
假如我这里有一个烧杯 里面,盛有一百万条蓝色DNA双链和,一百万条红色DNA双链,然后我稍微加热一下烧杯,并且加一些碱,很快我就有了四百万条DNA单链,漂浮在溶液里,因为我已经使得氢键断裂,DNA双链也随之打开
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