Or you could ask the question, I have this restriction enzyme, at what regions on this plasmid will it cut?
你也可以这样问,我的这种限制性内切酶,会从质粒的哪个区域切开呢
Cutting involves enzymes called restriction endonucleases or restriction enzymes, which I've already mentioned and they have names.
切割用到的酶叫限制性核酸内切酶,或限制性内切酶,我已经提到过了,而且它们都有名字
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
In this case, this particular restriction enzyme cuts symmetrically like this, but not at the same point.
在我们这种情况下,这个限制性内切酶总是这样对称地切割,但两条链切割的位点不一样
That's an example of symmetric sequence and it happens that most restriction enzymes also recognize those spaces.
这是一个对称序列的例子,大多数限制性内切酶都能识别这些序列
This restriction enzyme was found in a natural source, it was found in a micro-organism called E.coli.
这个限制性内切酶源于自然界,是从名为大肠杆菌的微生物中发现的
Now we know so much about these, they've turned out to be so useful in biotechnology.
现在我们对限制性内切酶了解这么深入,它们在生物技术方面又这么有用
They do that in a very special way in that they - restriction enzymes are able to identify a particular sequence of bases in a gene.
限制性内切酶的工作机制很特别,它能识别基因中的一段特定的碱基序列
There are whole catalogs that you go to and buy restriction enzymes.
我们已经可以从整本的目录上,挑选购买限制性内切酶
That cutting is done by special proteins called restriction enzymes.
切割是由一种特别的蛋白质完成的,称为限制性内切酶
What are the properties of this restriction enzymes?
这种限制性内切酶的特性是什么
There's whole families of restriction enzymes.
限制性内切酶是一个大家族
What restriction will do that?
哪种限制性内切酶可以做到
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
Restriction enzymes have names, The names all look - they're all italicized and they're capital letters and small letters so that they won't be easy for you to understand, but they are - if you know the nomenclature, easy to understand.
限制性内切酶有自己的名字,名字看起来都很--,都是斜体的,大写小写字母混合,你们不太容易理解,但它们都是--如果你懂命名法,是很容易理解的
Now another property of restriction enzymes is that they always cut the DNA in the same way.
限制性内切酶的另一个特性是,总是以同样的方式切割DNA
It was found in strain R, a particular strain of E.coli, and it was the first one found, There's a nomenclature that's evolved for this.
酶被发现于R菌株,大肠杆菌中一种特别的菌株,又是被发现的第一种内切酶,有一种专门为此制定的命名法
Most restriction enzyme also recognize symmetric sequences of DNA, GAATTC for example.
大多数限制性内切酶,也能识别DNA的对称序列,例如GAATTC
Restriction enzymes are just a kind of enzyme, enzymes are protein molecules that make a chemical reaction go faster, and the chemical reaction that restriction enzymes do is cutting DNA.
限制性内切酶是一种酶,而酶是加速化学反应的蛋白质分子,限制性内切酶加速的化学反应,是切割DNA
If I cut both the plasmid and my DNA of interest with the same restriction enzyme I'm going to end up with the same sticky ends on both molecules.
如果用同一种限制性内切酶,来切割质粒和我感兴趣的DNA,在两个分子上就能得到同样的粘性末端
This gives you a biological mechanism for cutting, using restriction enzymes, and then you denature so that it falls apart, and then you renature so that it comes back together.
这是一种切割DNA的生物机制,用限制性内切酶,改变DNA的性质让它打开,然后让它合起来恢复它的性质
This particular restriction enzyme here recognizes this sequence,GAATTC.
这里的这种限制性内切酶,只识别序列GAATTC
Well the first step would be to cut open the plasmid with a particular restriction enzyme, and then what if I take that same restriction enzyme and I cut up the DNA that I'm interested in.
第一步是用某种限制性内切酶把质粒切开,然后用同一种限制性内切酶,切出我想要的DNA
Now if I put them in contact with one another, the plasmid that's been opened and fragments of the DNA - special fragments that I've produced with the same restriction enzyme, they'll have the same sticky ends, they will naturally hybridize with one another.
如果我让它们互相接触,已经切开的质粒和DNA片段--,这DNA片段是我已用同种限制性内切酶,处理过的特别片段,这两者会有相同的粘性末端,它们会自然地相互杂交
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