问几个生物题（全是英文写的）1.Cells and Genetics question:How do some cells become brain cells and others become skin cells when the DNA in ALL the cells is exactly the same?2.Why is RNA necessary to act as a messenger?Why can't the cod

问几个生物题（全是英文写的）1.Cells and Genetics question:How do some cells become brain cells and others become skin cells when the DNA in ALL the cells is exactly the same?2.Why is RNA necessary to act as a messenger?Why can't the cod
问几个生物题（全是英文写的）
1.Cells and Genetics question:How do some cells become brain cells and others become skin cells when the DNA in ALL the cells is exactly the same?
2.Why is RNA necessary to act as a messenger?Why can't the code be taken directly from the DNA?

问几个生物题（全是英文写的）1.Cells and Genetics question:How do some cells become brain cells and others become skin cells when the DNA in ALL the cells is exactly the same?2.Why is RNA necessary to act as a messenger?Why can't the cod
问题一：细胞和基因方面问题：所有细胞中的DNA基本都是一样的,为什么有的细胞分化成了脑细胞,而其他的变成了表皮细胞?
虽然每个细胞中的DNA序列基本相同,但是在形成胚胎和发育时,不同细胞中的DNA受到特殊刺激等诱因会激发潜伏基因活跃起来并表达,从而完成细胞分化,形成具有不同功能的细胞.
问题二：为什么RNA也是不可或缺的遗传信息载体?为什么不是只需要DNA解译?
因为遗传信息的复制、转录、表达等需要几种特殊RNA的辅助才能完成,况且有的生物是没有DNA,只有RNA的.

1。cells，遗传学问题:如何做有些细胞成为脑细胞等等成为皮肤细胞当基因在所有细胞究竟同一?2。why核糖核酸必要充当一个信使?为什么可以't码失守直接从基因?

xcvbvcbxvb

1细胞和遗传学的问题：当DNA在所有的细胞里刚好相同时一些细胞怎样成为脑细胞和皮肤细胞？2：为什么核糖核酸必须充当一个媒介？为什么代码不能直接被DNA带着

（1）如何成为脑细胞的一些细胞变成皮肤细胞和其他人时，在所有DNA的细胞是完全一样的？
在生物体中的每个细胞，如人的DNA，确实是相同的。
It is like an encyclopedia.它就像一本百科全书。 But in every cell only some of the pages of the encyclopedia are open and being rea...

全部展开

（1）如何成为脑细胞的一些细胞变成皮肤细胞和其他人时，在所有DNA的细胞是完全一样的？
在生物体中的每个细胞，如人的DNA，确实是相同的。
It is like an encyclopedia.它就像一本百科全书。 But in every cell only some of the pages of the encyclopedia are open and being read.但是，只有在每一个细胞的百科全书某些页面是公开和未读的。
Enough of that encyclopedia metaphor!够了百科全书比喻！ We have about 20,000 genes , which determine how we turn out as we grow and develop, and as cells differentiate.我们有大约20,000 的基因 ，它决定我们如何变成随着我们的成长和发展，并随着细胞分化。 Every one of these genes is represented in every cell - twice, in fact, as there is one copy of the gene from Mom and one from Dad.这些基因的每一个是代表在每一个细胞 - 两次，事实上，因为有一份从基因和爸爸妈妈之一。
But in every cell only some of the genes are active .但是，只有在每一个细胞的一些基因被激活。 For example, there are genes for making hair and fingernails.例如，有用于制造头发和指甲的基因。 But those genes are not active in most cells, otherwise we would be sprouting hair all over the liver and nails from the tips of our noses.但是，这些基因是最不活跃的细胞，否则我们将在肝脏和萌芽从我们的鼻子尖指甲头发。
When some genes are activated, and the cell as a result makes the proteins that they code for, we say that the genes are being expressed .当某些基因被激活，结果使细胞的蛋白质作为他们的代码，我们说的基因
（2）为什么是RNA必要充当信使？ Why can't the code be taken directly from the DNA?为何不能采取直接从代码的DNA？
Because there's one copy of the gene in DNA (2 for diploid species including humans). It would take a LONG time to make an appreciable amount of protein from two copies of the gene. But the cell can make many copies of mRNA to quickly make larger amounts of the desired protein因为有一个在DNA复制的基因（包括人类二倍体物种为2）。 It would take a LONG time to make an appreciable amount of protein from two copies of the gene.这将需要很长的时间，使两个基因的拷贝数量可观的蛋白质。 But the cell can make many copies of mRNA to quickly make larger amounts of the desired protein.但细胞可利用基因副本的数量迅速作出更大的所需的蛋白质数量。

收起