单选题人体内嘌呤核苷酸分解代谢的代表性终产物是

单选题A．生长因子B．调节基因C．野生型P53基因D．噬菌体E．基因易位

单选题在复制和转录中均起作用的是______ A.RNA引物 B.DNA聚合酶 C.NMP D.dNTP E.蛋白质因子

单选题生理常温下，脂质双分子层的状态是______。

单选题由于碱基突变使编码Cys的密码子TGC突变为TGA，这种突变称为：

单选题脂酰CoA经过一次β-氧化；其产物乙酰CoA通过三羧酸循环和呼吸链氧化磷酸化，共生成ATP分子

单选题不是原癌基因产物的是

单选题测定酶活力时，反应速度对底物为______。

单选题真核生物BAN聚合酶Ⅱ催化的转录产物是

单选题RNA中含稀有碱基最多的是

单选题大肠杆菌共有几种DNA聚合酶______ A.1 B.2 C.3 D.4 E.5

单选题5-FU的抗肿瘤作用的生化机制为

单选题检测蛋白质-蛋白质相互作用的方法不包括：

单选题糖异生途径是指

单选题大肠杆菌DNA同源重组过程中，决定了同源重组异源双链区长度的蛋白质是：

单选题DNA分子经加热或加入过量的碱、酸均可使之变性，而变性因素去除以后又可复性，这一原理广泛用于核酸实验。DNA分子变性后

单选题Rarely do major diseases have a single cause. They are usually the result of a complex interaction between many factors, including genetic, environmental and lifestyle components. Many media reports, however, can tead us to believe that if we gave up something that we might otherwise enjoy, we could completely escape that particular affliction. Clearly, this is not the case. Vegetarians die of cancer of the colon (结肠). Teetotallers die of liver complaints, including cirrhosis (硬化). People who never go out in the sun contract skin melanomas (黑素瘤). Always, there are other factors at work than the single element being examined in a scientific study. Quite often the alleged benefits of a particular nutritional element are the result not so much of the element itself but of the lifestyle and general diet of the people who consume it most. People who eat lots of "healthy" foods, including fiber, carrots, broccoli etc. , also tend to drink less alcohol, take more exercise, avoid too many fatty foods and smoke less. Only when a study can rule out all of these other factors and often we do not know what these factors might be can we say that there is a causal link between two things. That is not to say that things like fiber and broccoli have no beneficial effects at all. But those with sedentary lifestyles cannot expect these foods to make them healthy. There is, however, one thing which increases the likelihood of dying relatively young, even when all of the other factors have been taken into account. It is one of the biggest killers even among those who lead lifestyles which, by any criteria, are clearly healthy ones. This single, incontrovertible risk factor is that of being poor. Recent report from the Cancer Research Campaign suggested that 12 700 deaths could have been avoided between 1986 and 1990 if inequalities in cancer care did not exist in England and Wales. Comparing cancer survival rates, the study found that England and Wales fared unfavorably with Europe and the US, but the most affluent regions of these two countries exhibited similar figures to the European average. In an attempt to counter this disparity the government has announced plans for the provision of Health Action Zones which seek to encourage greater cooperation between health and social services, targeting both rural and inner city areas. The emphasis of this new scheme however appears to focus on inadequacies within health education in these areas, rather than attacking the broader issues of social inequality.

单选题影响Hb与氧结合的因素是______。

单选题关于G蛋白的叙述中，错误的是

单选题脂肪酸β-氧化过程中脂酰CoA脱氢的受氢体为