单选题以下哪项不是转座的遗传效应( ) A．引起插入突变 B．可产生新基因 C．可形成共整合体 D．可引起基因失活 E．不进行DNA复制

单选题下列______不是蛋白质的性质之一。

单选题反式作用因子指的是 A.具有激活功能的调节蛋白 B.具有抑制功能的调节蛋白 C.能激活自身基因表达的调节蛋白 D.能抑制自身基因表达的调节蛋白 E.能调节另一基因表达的调节蛋白

单选题蛋白质分子中α-螺旋的特点是(　　　)

单选题下列蛋白质通过凝胶过滤层析时最先被洗脱的是( )(2000年)

单选题体内脂酸合成的关键酶是

单选题有关成熟红细胞代谢特点的叙述，错误的是 A.成熟红细胞无线粒体，靠糖酵解供能 B.ATP主要用来维持红细胞膜的钠泵、钙泵功能 C.红细胞内的糖酵解主要通过2，3-BPG支路生成乳酸 D.人红细胞内的谷胱甘肽是主要的抗氧化剂 E.红细胞内有少量MHb产生，但可以在还原酶催化下使其还原

单选题某人摄取110g蛋白质，24h后从尿中排出尿素17g，粪便中排出氮3g，他的氮代谢处于

单选题原核生物经转录作用生成的mRNA是

单选题顺式作用元件的化学本质是( ) A．DNA B．RNA C．tRNA D．rRNA E．多肽链

单选题下列反应中属于酶化学修饰的是( )(2012年)

单选题双向电泳中第二向SDS-聚丙烯酰胺凝胶电泳是根据蛋白质的哪个特点分离的?( ) A．所带电荷 B．等电点 C．分子量 D．分子形状 E．分子大小

单选题框移突变与密码子的哪项特性有关

单选题tRNA中的内含子( )。

单选题下面哪种酶在糖酵解和糖异生中都起作用

单选题小干扰RNA指的是 A.snRNA B.hnRNA C.dsRNA D.siRNA E.miRNA

单选题待测的DNA与标记DNA探针的杂交称为( )。

单选题Several years ago, at the height of the dotcom boom, it was widely assumed that a publishing revolution, in which the printed word would be supplanted by the computer screen, was just around the corner. It wasn't: for many, there is still little to match the joy of reading a printed book and settling down for one hour. But recently some big technology companies, including Google, Amazon, Microsoft and Yahoo, contend that the dream of bringing books online is still very much alive. The digitizing of thousands of volumes of print is not without controversy. On Thursday, Google, the world' s most popular search engine, posted a first installment of books on Google Print. This collaborative effort between Google and several world's leading research libraries aims to make books available to be searched and read online free of charge. Although the books included so far are not covered by copyright, the plan has attracted the rage of publishers. Five large book firms are suing Google for violating copyright on material that it has scanned and, although out of print, is still protected by law. Google has said that it will only publish short extracts from material under copyright unless given express permission to publish more, but publishers are unconvinced. Ironically, many publishers are collaborating with Google Print Publisher, which aims to give readers an online taste of books that are commercially available. The searchable collection of extracts and book information is intended to tempt readers to buy the complete books online or in print form. Amazon, the world's largest online retailer, has made plans to enter the mass e-book market by selling a vast array of goods. Given that Google should impinge upon its central territory, Amazon revealed that it would introduce two new services. Amazon Pages will allow customers to search for key terms in selected books and then buy and read online whatever part they wish. Amazon Upgrade will give customers online access to books they have already purchased as hard copies. Customers are likely to have to pay five cents a page, with the bulk going to the publisher. Microsoft has also joined the online-book trend. In October, the software giant said it would spend around $ 200 million to digitize texts, starting with I50,000 that are in the public domain, to avoid legal problems. It will do so in collaboration with the Open Content Alliance. And on Thursday, coincidentally the same day as Google and Amazon announced their initiatives, Microsoft released details of a deal with the British Library, the country's main reference library, to digitize some 25 million pages ; these will be made available through MSN Book Search, which will be launched next year.

单选题下列何种物质与苹果酸穿梭过程无关

单选题关于细胞癌基因描述不正确的是 A.存在于DNA和RNA肿瘤病毒 B.也称为原癌基因 C.激活后导致肿瘤 D.正常细胞基因组中存在 E.维持正常细胞生长等功能