看板Biotech
标 题Re: [问题] 一个遗传的选择题
发信站清华生命科学 BBS (Sun Jun 17 21:05:53 2007)
转信站ptt!Group.NCTU!grouppost!Group.NCTU!nthuls
> A restriction enzyme cuts DNA and leaves the following end: GGCTA
> C
> Which of the following could be the sequence of the corresponding end of the
> other fragment generated by the enzyme?
> A) CCGAT
> G
> B) GGCTA
> C
> C) C
> GGCTA
> D) T
> CGATA
> E> None of the above
I think this is a very tricky question (and a controversial one).
Normally a restriction enzyme cutting site needs to be symmetrical.
Therefore the complete sequence of the cutting site should be
5' GGCTAGCC...3'
3' CCGATCGG...5'
After digestion, it becomes
5' GGCTAGC C...3'
3' C CGATCGG...5'
Therefore, answer B seems to be a reasonable choice.
At least this is probably the professor who designed the quiz wants.
However, I really think this kind of quiz is misleading and will not
be useful in seleting good students.
--
※ Origin: 生命科学 BBS <bbs.life.nthu.edu.tw>
◆ From: 61-59-139-151.adsl.static.seed.net.tw
1F：推 thrush:thank you, but the given answer is D. 06/17 21:26
2F：推 yaliu:为什麽答案是D阿???? 06/18 00:07
3F：推 thrush:Sorry, that also confuse me. 06/18 09:23
4F：推 nightcatman:google可以找到那张考卷,说实在的出得很烂,英文也很烂 06/19 08:02
5F：→ nightcatman:我怀疑是研究生助教帮老师出的... 06/19 08:03
6F：推 b46006:我觉得是E 被切开的地方必须互补不是吗 06/19 11:37
7F：推 blence:D,是因为排版的问题T没有正确配对,把上面T拉到正确位就对了 06/19 12:58
8F：推 b46006:楼上真细心 06/19 14:12