2021-2022 英语周报 高考 XN 47答案

25.(8分,每空1分)(1)mRNA(2)DNA双链复制受热变性(或“高温变性”)热稳定DNA聚合(或“T(3)乳腺蛋白基因的启动子(4)Ca2+(或“caCl2”)能吸收周围环境中DNA分子感受态细胞【解析】(1)将某种生物发育到某个时期的mRNA反转录产生的多种互补的DNA(cDNA)片段,与载体连接后储存在一个受体菌群中,这个受体菌群就叫种生物的cDNA文库。hcR是一种体外DNA复制技术,其原理是DNA双链复制;首先目的基因受热变性(解旋)成为单链DNA,随后引物与单链相应互补序列结合,最后在热稳定DNA聚合酶(Taq酶)的作用下以脱氧核苷酸为原料进行延伸,如此重复循环(3)为了使目的基因如药物蛋白基因在乳腺细胞中顺利表达,通常将目的基因和乳腺蛋白基因的启动子等调控组件重组在一起,使之伴随着乳腺蛋白基因表达,通过分泌乳汁来生产所需的药品。(4)如果目的基因的受体细胞是大肠杆菌,为了提高导入效率,需要用氯化钙溶液处理细菌,使细胞处于容易吸收周围环境中DNA分子的状态,这样的细胞称为感受态细胞。

第二节One possible versionniceDear overseas students from America,Here comes the news that Chinese Bridge series activities will be held in our school. So all of participants arewarmly welcome in the pep rally to get fully prepared for thefolloThemed at promoting Chinese culture around theworld, Chinese Bridge acts as a platform to help narrow thegap of mutual understanding about China. Whoever isactively involved in it will develop a positive awareness ofChinese and its culture behind. Based on it, the pep rallis scheduled in our school auditorium from 14: 00 p.m15: 00 P. m. next Friday afternoonPlease make sure you are available at that time andThe student’ s Union

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