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北京石油化工学院2026年研究生招生接收调剂公告
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kikiwitch

新虫 (初入文坛)


[交流] 一道非常考基本功的题。

在某主页上看见一堆分子生物学的题,好考基本功啊!

这题看了答案也没想明白,各位看看题讨论讨论。

It is possible to obtain mutations in plasmid encoded genes by mutagenizing the purified plasmid DNA in vitro (for example, with hydroxylamine) then transforming the plasmid DNA into recipient cells. Given a plasmid that encodes ampicillin resistance (AmpR), chloramphenicol resistance (CamR), and B-galactosidase (lacZ), how would you use this approach to isolate single mutations in the lacZ gene? Be sure to describe any genetic selections and/or screens used. [Hint: you will need a way of measuring the relative amount of mutagenesis to ensure a reasonable probability that the lacZ mutants are due to a single mutation.]

ANSWER:

    Mutagenize the purified plasmid DNA in vitro with hydroxylamine.
    Move the plasmid into a lacI- lacZ+ lacY+ host (by transformation or electroporation of the plasmid DNA), selecting for chloramphenicol resistance.
    Screen the cells for (i) AmpR and (ii) repression of lacZ (for example, by screening for X-gal- in the absence of an inducer such as lactose or IPTG).
    In several independent experiments, quantitate the extent of mutagenesis by plotting the number of Amps mutants and the number of LacI- mutants vs time of exposure to the mutagen. The results will indicate the number of cells that have a mutation in both genes (i.e. at least two hits) compared to the number of cells that have a mutation in only one gene (i.e. at least one hit). These results can be plugged into the Poisson distribution to determine the probability of 0, 1, and >1 hit per gene for each time point. Choose colonies from time points where the probability of >1 hit per gene is rare.

[ Last edited by 1949stone on 2013-6-6 at 08:08 ]
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owdyq32

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本帖内容被屏蔽

2楼2013-06-06 11:38:11
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songzuowei

木虫 (著名写手)



小木虫: 金币+0.5, 给个红包,谢谢回帖
这玩意一堆英语符号,看的头都大了
3楼2013-06-06 12:00:16
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kikiwitch

新虫 (初入文坛)


引用回帖:
2楼: Originally posted by owdyq32 at 2013-06-06 11:38:11
抢抢沙发吧

好像沙发没抢上啊
4楼2013-06-06 22:59:16
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516860360

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小木虫: 金币+0.5, 给个红包,谢谢回帖
英语不好表示鸭梨山大
5楼2013-06-07 10:48:57
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天涯鸿影

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小木虫: 金币+0.5, 给个红包,谢谢回帖
LZ求此主页网址,去学习下~
6楼2013-06-07 12:15:15
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