单选题针对配基的生物学特异性的蛋白质分离方法是______。

单选题基因工程技术中实现目的基因与载体DNA连接的酶是( )。

单选题下列哪项不属于真核生物基因的顺式作用元件______ A.激素反应元件 B.衰减子 C.启动子 D.沉默子 E.增强子

单选题体内生成核糖的主要途径是(　　　)

单选题2003年诺贝尔化学奖授予研究生物膜上通道蛋白的科学家，他们阐明了______。

单选题识别碱基改变的感应因子是( ) A．ATM B．ATR C．Chk1 D．Chk2 E．Cdc25A

单选题理想冠桩外形的要求是

单选题RNAi技术的基本程序主要为 A.siRNA对目标RNA的干扰、确定干扰靶点、合成siRNA B.确定干扰靶点、合成siRNA、siRNA对目标RNA的干扰 C.siRNA对目标RNA的干扰、合成siRNA、确定干扰靶点 D.确定干扰靶点、siRNA对目标RNA的干扰、合成siRNA E.合成siRNA、确定干扰靶点、siRNA对目标RNA的干扰

单选题严重肝病时，机体各器官会发生出血倾向，主要原因是 A.维生素A减少 B.维生素B6减少 C.维生素C减少 D.维生素E减少 E.维生素K减少

单选题Prince Klemens Von Metternich, foreign minister of the Austrian Empire during the Napoleonic era and its aftermath, would have no trouble recognizing Google. To him, the world's most popular web-search engine would closely resemble the Napoleonic France that in his youth humiliated Austria and Europe's other powers. Its rivals—Yahoo!, the largest of the traditional web gateways, eBay, the biggest online auction and trading site, and Microsoft, a software empire that owns MSN, a struggling web portal—would look a lot like Russia, Prussia, and Austria. Metternich responded by forging an alliance among those three monarchies to create a "balance of power" against France. Google's enemies, he might say, ought now to do the same thing. Google announced two new conquests on August 7th. It struck a deal with Viacom, an "old" media firm, under which it will syndicate video clips from Viacom brands such as MTV and Nickelodeon to other websites, and integrate advertisements into them. This makes Google the clear leader in the fledgling but promising market for web-video advertising. It also announced a deal with News Corporation, another media giant, under which it will pro-vide all the search and text-advertising technology on News Corporation's websites, including My Space, an enormously popular social-networking site. These are hard blows for Yahoo! and MSN, which had also been negotiating with News Corporation. Both firms have been losing market share in web search to Google over the past year—Google now has half the market. They have also fallen further behind in their advertising technologies and networks, so that both make less money than Google does from the same number of searches. Safa Rashtchy, an analyst at Piper Jaffray, a securities firm, estimates that for every advertising dollar that Google makes on a search query, Yahoo! makes only 60-70cents. Last month Yahoo! said that a new advertising algorithm that it had designed to close the gap in profitability will be delayed, and its share price fell by 22% , its biggest-ever one-day drop. MSN is further behind Google than Yahoo! in search, and its parent, Microsoft, faces an even more fundamental threat from the expansionist new power. Many of Google's new ventures beyond web search enable users to do things free of charge through their web browsers that they now do using Microsoft software on their personal computers. Google offers a rudimentary but free online word processor and spreadsheet, for instance. The smaller eBay, on the other hand, might in one sense claim Google as an ally. Google's search results send a lot of traffic to eBay's auction site, and eBay is one of the biggest advertisers on Google's network. But the relationship is imbalanced. An influential re-cent study from Berkeley's Haas School of Business estimated that about 12% of eBay's revenues come indirectly from Google, whereas Google gets only 3% of its revenues from eBay. Worst of all for eBay, Google is starting to undercut its core business. Sellers are setting up their own websites and buying text advertisements from Google, and buyers are using its search rather than eBay to connect with sellers directly. As a result, "eBay would be wise to strike a deep partnership with Yahoo! or Microsoft in order to regain a balance of power in the industry," said the study's authors, Julien Decot and Steve Lee, sounding like diplomats at the Congress of Vienna in 1814.

单选题 真核起始因子eIF-3的作用是： A、帮助形成亚基起始复合物（eIF-3，GTP，Met-tRNA，40S） B、帮助亚基起始复合物（三元复合物，40S）与mRNA5′端的结合 C、若与40S亚基结合，防止40S与60S亚基的结合 D、与mRNA5′端帽子结构相结合以解开二级结构 E、激活核糖体GTP酶，使亚基结合可在GTP水解时结合，同时释放eIF-2

单选题关于肽单元的叙述，错误的是

单选题体内最广泛存在，活性最高的转氨酶是

单选题关于内含子叙述错误的是

单选题阻遏蛋白结合乳糖操纵子的( ) A．P序列 B．O序列 C．CAP结合位点 D．I基因 E．Z基因

单选题建cDNA文库时，首先需分离细胞的( )。

单选题下列哪一种类型的酶可能不参与切除修复(Excisional Repair)______。 A．DNA聚合酶 B．RNA聚合酶 C．DNA连接酶 D．解旋酶(helicase) E．外切酶(exonuclease)

单选题关于多顺反子，描述正确的是( ) A．一个结构基因由不同的调控序列调控 B．几个结构基因由不同的启动子调控转录 C．一个多顺分子有多个功能相关的结构基因 D．多个结构基因编码一类蛋白质 E．一个结构基因编码多种蛋白质

单选题编码小分子G蛋白的癌基因是

单选题A．丙酮酸B．谷氨酸C．α-酮戊二酸D．甘氨酸