[求助]大全36

wangyu73cn

我看了你的问题也觉得头晕了。谁能回答你这么多的而且又是非具体的问题啊？：）只好将就先把文章看看了。至于问题，需要楼主具体解释一下自己的疑惑才好让大家帮忙。

Protein synthesis begins when the gene encoding a protein is activated.
蛋白质合成，是自相应基因激活开始的。

The gene’s sequence of nucleotides is transcribed into a molecule of messenger RNA (mRNA), which reproduces the information contained in that sequence.
基因的次序传给MRNA。

Transported outside the nucleus to the cytoplasm, the mRNA is translated into the protein it encodes by an organelle known as a ribosome, which strings together amino acids in the order specified by the sequence of elements in the mRNA molecule.
从细胞核进入细胞质，MRNA经由R这种细胞器转化为蛋白质。R这个细胞器和氨基酸缠绕在一起，其缠绕次序由MRNA的次序来确定。

Since the amount of mRNA in a cell determines the amount of the corresponding protein, factors affecting the abundance of mRNA’s play a major part in the normal functioning of a cell by appropriately regulating protein synthesis.
由于MRNA的数量确定相应蛋白质的数量，影响MRNA数量的因素就很重要了。

For example, an excess of certain proteins can cause cells to proliferate abnormally and become cancerous; a lack of the protein insulin results in diabetes.
例如，某种蛋白质超量可导致细胞非正常扩散并癌变；缺乏胰岛素蛋白质则导致糖尿病。

Biologists once assumed that the variable rates at which cells synthesize different mRNA’s determine the quantities of mRNA’s and their corresponding proteins in a cell.
生物学家曾认为细胞合成MRNA的不同速率决定了量。

However, recent investigations have shown that the concentrations of most mRNA’s correlate best, not with their synthesis rate, but rather with the equally variable rates at which cells degrade the different mRNA’s in their cytoplasm.
但，近期研究表明，不是合成速度，而是分解速度更为重要。

If a cell degrades both a rapidly and a slowly synthesized mRNA slowly, both mRNA’s will accumulate to high levels.
如果分解慢，快速合成和慢速合成的都将达到高水平。

An important example of this phenomenon is the development of red blood cells from their unspecialized parent cells in bone marrow (bone marrow: n. 骨髓).
一个重要的例子是，红血球在骨髓种的成长。

For red blood cells to accumulate sufficient concentrations of hemoglobin (hemoglobin: n.血色素) (which transports oxygen) to carry out their main function, the cells’ parent cells must simultaneously produce more of the constituent proteins of hemoglobin and less of most other proteins.
为了红血球积累足够的血色素，母细胞必须同时产出较多的血色素和较少的其他蛋白质。

To do this, the parent cells halt synthesis of non-hemoglobin mRNA’s in the nucleus and rapidly degrade copies of the non-hemoglobin mRNA’s remaining in the cytoplasm.
为此，母细胞中断细胞核中非血色素MRNA的合成并加速细胞质中对其的分解。

Halting synthesis of mRNA alone would not affect the quantities of proteins synthesized by the mRNA’s still existing in the cytoplasm.
仅中止细胞核中的合成是无效的。

Biologists now believe that most cells can regulate protein production most efficiently by varying both mRNA synthesis and degradation, as developing red cells do, rather than by just varying one or the other.
所以，要双管齐下。

wangyu73cn

5.     To begin to control a disease caused by a protein deficiency, the passage suggests that a promising experimental treatment would be to administer a drug that would reduce

如何控制蛋白质缺乏症？我们不妨自己先想想。
从文章来看，应该是减慢MRNA的分解速度(A选项所示)，或同时再加快其合成，所以A对。only the degradation rate for the mRNA of the protein involved
B反，错。only the synthesis rate for the mRNA of the protein involved
C部分反，错。both the synthesis and degradation rates for the mRNA of the protein involved
无关，错。the incidence of errors in the transcription of mRNA’s from genetic nucleotide sequences

wangyu73cn

第8题的C不对。我认为，首先要明确C的意思，即“一旦发现蛋白质高含量，就可能发生增生和癌变。”文中根本没有这个意思。其实，C描述的是比较恐怖的事情，因为正常组织中的某种蛋白质是常常位于高水平的。例如饭后胰岛素量大，但显然不能说可能癌变。请再考虑一下C的准确意思，而不能依靠“大概和文章一致”或“关键词的再现”来选择答案。

wangyu73cn

以下是引用wanderdreaｍ在2005-7-28 20:13:00的发言：

如红色部分考虑的话，不是引入了文章并没有表述的专业知识了吗？

文章说了，an excess of certain proteins can cause cells to proliferate abnormally and become cancerous; a lack of the protein insulin results in diabetes

而我认为C说由于这些蛋白质偏高可能导致癌变，这个本身没错，只是文不对题，不能回到问题。如小猫妹妹所言

喔，我想再说明一下：首先，我所说的“其实，C描述的是比较恐怖的事情，因为正常组织中的某种蛋白质是常常位于高水平的。例如饭后胰岛素量大，但显然不能说可能癌变。”的确不是文章中所反应的内容，这只是我的补充说明，是为了说明，离开本文考虑一下，C很怪异。

而C的错误根源在于，文章中是说certain，而问题中没有certain这个限定,所以C就存在将各种蛋白质全包括的问题，所以就不对了。