Retroviruses, for example, can only insert - can only transduce and express their DNA in cells that are dividing.
就以逆转录病毒为例,它们只能在分裂阶段的细胞里,转导并表达自己的基因
We talked about mitosis last time; it's described more completely in the chapter, where two cells are formed from one.
我们上节课说到过有丝分裂,在那一章里更详细的阐释了,细胞是怎么由一生二的
So this means we can code for it in DNA, you don't have to worry how am I going to get into the cell.
这意味着我们可以在DNA中编写它,你不用担心它怎么进到细胞里去。
You know probably that within your bone marrows there's populations of cells, there are different kinds of cells within the bone marrow.
你也许知道的,在你的骨髓里,有许多种细胞,骨髓中有不同种类的细胞
Because of that you can't count on molecules moving rapidly over the size of a cell that's ten to 30 Microns in diameter.
因此不要对生物大分子能在,直径十到三十微米的,细胞里高速穿行抱有任何指望
You're not fishing through a whole chromosome in order to find what you want, but you're going to a cell that's already enriched in it.
你不是大海捞针地,在一整个染色体中找基因,而是在一个充满了,你感兴趣的基因的细胞里找
In Week 3 you'll actually do some cell culture in the laboratory and look at cultured cells and learn how to manipulate, do some manipulations on cells and culture, and so on throughout the weeks.
第三周你们会在实验室里做一些细胞培养,看看培养基中的细胞都长什么样,了解细胞和培养基的有关操作,整个一周就做这些
That makes sense if you think about this process of cell multiplication, that I have one cell it becomes 2 cells in a minute, it could become 4 cells in another minute, it could become 8 cells in another minute and that's all that this set of equations is representing.
如果你和细胞增殖的过程联系起来的话,这个是说的通的,我有一个细胞在一分钟里变成了两个细胞,那就可以再花一分钟变成四个细胞,再花一分钟就变成八个细胞,这就是这个方程所代表的意义
That's synthesis and that has to happen in order for cells to replicate and cell replication is happening in your body all the time.
这个DNA合成过程是,细胞复制中不可或缺的部分,细胞复制时刻不停的在你身体里进行着
So how can cells, which have the same sort of master information DNA, in your brain, and your heart, and your kidney be so different?
那么为什么这些有同种DNA信息的细胞,在你的大脑里,你的心脏里,在你的肾里,表现的如此不同呢
It gets converted into a protein, insulin, only in those cells that are able to make the RNA that are able to express the protein.
只有在能表达,胰岛素蛋白RNA的细胞里,基因才能指导产生胰岛素
Plus,if you're looking for insulin, if you're looking for the gene for insulin you're going to cells that are making it already, they have abundant messenger RNA so it's much easier to separate out and identify the gene that you're interested in.
再者,如果你在找胰岛素,如果你在找胰岛素基因,你要到,正在制造胰岛素的细胞里找,里面有丰富的mRNA,所以更容易分离,并识别出你感兴趣的基因
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