2022英语周报 北师大高一北师大26期答案

(除注明外,每空2分,共15物,减少杆直接还导致的有(1)识别的特异性更高(2)靶位点能表达Cas9蛋白和特异的向导RNA农杆菌植物组织培养(3)增强将正常水稻和 SERF922基因敲除水稻分别接种子囊菌,观察对比两者稻瘟病的发病状况(3分)解析:(1)依图示信息可知,Cas9蛋白对目标DNA分子进行精准定位,对目标位点进行准确切割,依赖于核酸制酶,但是它比限制酶更具备的优势是识别的特异性更高。(2)结合基因工程的基本步骤可知,利用 CRISPR/Cas9技术获得了水稻 SeRF922基因敲除植株的步骤为:根据 SeRF922基因序列,选择合适的靶位点,设计向导RNA,然后利用PCR反应得到向导RNA对应的DNA片段,将该片段连接到 CRISPR/Ca9载体上,得到CRISPR/Cas9基因表达载体; CRISPR/Cas9基因表达载体应该具备的能力是能表达Cas9蛋白和特异的向导RNA,以实现定向改造的目的;将目的基因导人水稻细胞常用方法为农杆菌转化法,故可将 CRISPR/Cas9基因表达载体导入农杆菌,并用它侵染水稻细胞;将水稻细胞培养为水稻植株的方法为植物组织培养技术。(3)结合题意“下调 OSERF922基因的表达能提高植物与防御相关的一些基因的表达量”,据此可推测 OSERE922基因敲除水稻植株( SERF922基因少)对稻瘟病的抵抗力会增强;为证明上述结论,则实验的自变量为OERF922基因的有无,因变量为水稻稻瘟病的发病状况,故可设计实验如下:将正常水稻和 OSERE922基因敲除水稻分别接种子囊菌,观察对比两者稻瘟病的发病状况。

书面表达One possible version:NOTICEA sports meeting will be held in the playground of our school from next Thursday to FridayAs you know, the pressure of study is very heavy now, especially for those senior 3. So the purpose of the sports meeting is to letevery student get relaxed, as a result of which we students can live happily and heal thilyEveryone is welcome to take part in it. Those who perform excellently at the sports meeting will get prizes. But don' t take theresults so serously because taking part is more important than the result. Good luck to everyone!

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