单选题竞争性抑制时，酶促反应表现K
m
值的变化是
单选题起始密码子AUG同时可编码哪种氨基酸
单选题胶原蛋白中最多的氨基酸残基是______。
单选题有一蛋白质水解物，在pH6时，用阳离子交换柱层析，第一个被洗脱的氨基酸是______。
单选题下列关于逆转录酶的叙述，错误的是
单选题A．cGMP依赖的蛋白激酶
B．酪氨酸蛋白激酶
C．cAMt依赖的蛋白激酶
D．Ca
2+
磷脂依赖的蛋白激酶
E．钙调蛋白依赖的蛋白激酶
单选题
tRNA在蛋白质生物合成中的作用是
A、携带遗传密码 B、提供蛋白质合成的场所
C、运输氨基酸 D、指导氨基酸的合成
单选题以下哪项技术常用于基因诊断中( ) A．PCR B．双向电泳 C．飞行质谱 D．酵母双杂交 E．基因敲除
单选题在鸟氨酸循环中，直接生成尿素的中间产物是( )(2010年)
单选题Did you ever have someone's name on the tip of your tongue and yet you were unable to recall it? (1) this happens again, do no (2) to recall it. Do something (3) for a couple of minutes, (4) the name may come into your head. The name is there since you have met (5) person and his name. It (6) has to be dug out. The initial effort to recall (7) the mind for operation, but it is the subconscious (8) that go to work to dig up a (9) memory. Forcing yourself to recall (10) never helps because it doesn't (11) your memory；it only tightens it. Students find the preparatory method help (12) examinations. They read over the questions (13) trying to answer any of them. (14) they answer first the ones (15) which they are most confident. Meanwhile, deeper mental activities in the subconscious mind are taking (16) ; work is being done on the (17) difficult questions. By the time the easier questions are answered, answers (18) the more difficult ones will usually begin to (19) into consciousness. It is often (20) a question of waiting for recall to come to the memory.
单选题以下多肽序列中，哪个最有可能形成α螺旋结构______。
单选题维生素D的主要生化作用是
单选题在真核生物细胞中tRNA的转录是由( )。
单选题下列有关三羧酸循环的叙述中正确的是
单选题下述氨基酸能直接脱去氨基变成α-酮酸的为( )
单选题亚二倍体是指( )。
单选题有关核酶的哪种表述是不正确的( ) A．具有引导序列 B．具有锤头状结构 C．切断目的mRNA而自身没有消耗 D．核酶两端的引导序列与靶分子序列互补 E．使mRNA不能转录
单选题大鼠出生后饲以去脂膳食，结果将引起下列哪种脂质缺乏( )(1999年)
单选题脑中氨的主要去路
单选题为了分析小鼠肝脏组织中某一特定基因在不同条件下表达水平的变化，可能采用的实验手段是______。 A．Southern杂交 B．Nonhem杂交 C．酵母双杂交 D．荧光原位杂交