相关试题
【多选题】
测定酶活力时必须做到
A. 知道酶的分子量
B. 控制反应的温度
C. 使用有限量的底物
D. 在规定时间内测定底物的减少量或产物的生成量
E. 保持酶的足够浓度
【多选题】
下列酶促反应的叙述哪些是正确的
A. 底物浓度过量和不受限制时反应速度与酶浓度成正比
B. 底物浓度过量时反应呈零级反应
C. 底物浓度低时反应速度与底物浓度成正比
D. 底物浓度与酶浓度相等时可达最大反应速度
E. 底物浓度低时反应速度与酶的浓度成正比
【多选题】
测定酶活性的必要条件是
A. 最适pH
B. 适宜温度
C. 足够的底物
D. 反应体系中不含激活剂
E. 适宜的辅助因子
【多选题】
下列关于酶活性中心的叙述哪些是正确的
A. 由催化基团和结合基团组成
B. 能与底物结合并将底物转化成产物
C. 结合基团结合底物和辅酶
D. 酶的必需基团必定是酶活性中心的组成部分
E. 辅酶或辅基参与酶活性中心的组成
【多选题】
根据米曼氏方程式有关[S]与Km之间关系的说法哪些是正确的
A. 当[S]<< Km时υ与
B. 当[S] Km时υ= Vmax /2
C. 当[S]>> Km时反应速度与底物浓度无关呈零级反应
D. 当[S]=1/3Km时V=25%VmaxE.当[S] Km时υ= Vmax /3
【多选题】
下列有关酶的竞争性抑制作用的叙述哪些是正确的
A. 抑制剂的结构与底物的结构相似
B. 对Vmax无影响
C. 增加底物浓度可减弱抑制剂的作用
D. 使Km值变小
E. 使表观Km增大
【多选题】
下列关于抗代谢物的概念哪些是正确的
A. 一般是酶的竞争性抑制剂
B. 结构与特定的天然化合物相似
C. 有的可用于治疗感染
D. 可用于确定代谢途径的反应顺序E.一般对酶无作用
【多选题】
多酶体系中的限速酶往往是
A. 催化的反应速度最慢的酶
B. 可以通过变构调节或化学修饰调节而改变活性的酶
C. 常出现在多酶体系的起始或分支部位
D. 一个体系中仅有一个限速酶存在
E. 它的活性决定整个代谢途径的方向
【多选题】
变构酶的特点包括
A. 常由几个亚基构成
B. 多数是代谢途径中的关键酶
C. 分子内有与效应物结合的特殊部位
D. 效应物使酶的构象发生变化时酶的活性升高
E. 变构效应剂可以与某些酶分子活性中心外的某一部位可逆地结合
【多选题】
证明多数酶是蛋白质的证据是
A. 水解产物是氨基酸
B. 可被蛋白酶水解
C. 有和蛋白质一致的颜色反应
D. 可
【多选题】
常见的酶活性部位的必需基团有
A. 组氨酸的咪唑基
B. 丝氨酸的羟基
C. 半胱氨酸的巯基
D. 谷氨酸的γ羧基
E. 蛋氨酸的硫原子
【多选题】
关于变构酶正确的有
A. 变构酶催化的反应都是可逆的
B. 变构酶与变构效应物的结合是可逆的
C. 变构酶一定有催化亚基和调节亚基
D. 变构酶变构时常伴有亚基的聚合或解聚
E. 酶蛋白有可逆的共价变化
【多选题】
酶的化学修饰的特点正确的有
A. 酶蛋白有可逆的共价变化
B. 化学修饰最常见的是共价磷酸化
C. 化学修饰有放大作用
D. 酶的化学修饰与酶的变构无关
E. 酶蛋白有可逆的非共价变化
【填空题】
结合酶由______和______两部分组成二者结合成的复合物又称______。在结合酶中决定反应特异
【填空题】
酶的磷酸化由______催化而脱磷酸化由______催化。对限速酶快速调节的两种主要方式是______和
【填空题】
酶促反应的特点是酶促反应具有_______、_____和______。
【填空题】
在酶促反应中当底物浓度大大超过酶的浓度使酶被底物饱和时反应速度与酶的浓度成______关
【填空题】
根据抑制剂与酶结合的紧密程度不同酶的抑制作用分为______抑制和______抑制。酶的可逆性抑制
【填空题】
有机磷化合物使羟基酶失活的抑制作用属于酶的______抑制。______可解除这种抑制。重金属盐使巯
【填空题】
酶根据其组成不同可分为______和______两类仅有氨基酸残基构成的酶为______。酶的辅助因子根
【填空题】
酶的竞争性抑制剂的分子结构与______相似竞争性抑制剂与酶的______结合若增大底物浓度抑
【填空题】
酶分子中只有一条多肽链构成的酶称为______|由多个相同或不相同的亚基以非共价键连接的酶称
【填空题】
酶促反应具有极高的效率原因是由于酶能降低反应的______。
【填空题】
就化学本质而言酶原的激活过程就是______或暴露的过程。
【填空题】
酶结构的调节包括______调节和______调节。
【填空题】
米氏常数等于酶促反应速度为最大反应速度一半时的______可反映酶与底物亲和力的大小|Km值愈
【填空题】
Km值是指______最大反应速度一半时的底物浓度。
【填空题】
磺胺类药物与______酶的底物______的结构相似可抑制该酶的活性而抑制细菌生长。
【填空题】
在其它因素不变的情况下底物浓度的变化对反应速度的影响的作图呈______线双倒数作图呈______
【填空题】
非竞争性抑制作用中酶既可以与______结合又可以与______结合二者不存在竞争关系。非竞争
【填空题】
酶分子中与酶的活性密切相关的基团称作酶的______基团。活性中心内的必需基团包括______和
【填空题】
变构酶与一般酶不同的是酶分子中含有______部位可与______结合引起酶构象改变活性变化。
【填空题】
根据酶的特异性严格程度不同将其分为______、______、______三类。乳酸脱氢酶只催化L-乳酸的
【填空题】
反竞争性抑制物存在时酶反应动力学特点Vmax______Km______。
【填空题】
变构酶由多亚基组成按功能区分有的亚基为______亚基有的为______亚基。变构酶反应动力学
【填空题】
酶的快速调节方式包括______和______。
【填空题】
新生的酶的无活性前体称______转变为有活性的酶的过程为______。
【填空题】
如果一个酶能作用于多个底物其中一个是最适底物则它的Km值______。
【填空题】
酶所催化的反应称______在酶催化反应中被酶催化的物质称______反应生成物称______酶所具
【填空题】
酶的空间结构遭破坏时酶的______也被破坏酶的活性______。
推荐试题
【单选题】
15.Millie does __________ that many people are thankful to her．
A. such an important and helpful job B. so important and helpful work
C. a very important and helpful job D. such an important and helpful work
【单选题】
16. I think eating more vegetables is good _______ our health.
—Yes, I agree _______ you.
A. at, to B. for, with C. to, to D. for, to
【单选题】
17. I often go on holiday with my parents _____ summer.
A. in B. at C. on D. of
【单选题】
18. I called you at 4:00 yesterday afternoon, but nobody answered.
Sorry, I ______ with my friends at that time.
A. had swum B. swam C. would swim D. was swimming
【单选题】
19.––Who is on the playground? ---__________．
A. Never B. None C. No one D. A lot
【单选题】
20. The schoolboy ______ a blind man cross the street yesterday.
A. helps B. helped C. will help D. has helped
【单选题】
21. —The 2010 World Expo which will last 184 days will be held in Shanghai on May 1st.
—________exciting news! We shall try our best to support it.
A. How B. How an C. What D. What an
【单选题】
22. They preferred ______ in bed rather than _____ horses．
A. to lie; to ride B. lying; riding C. lying; ride D. to lie; ride
【单选题】
23. —What was Jim wearing at the party?
— Nothing _______. He was in his usual shirt and jeans.
A. special B. simple C. important D. interesting
【单选题】
24. The 2016 Olympic Games ________ in Brazil. Would you like to go there?
Maybe, if possible.
A. are held B. will be held C. were held D. have been held
【单选题】
25. — David, look at the man in white over there．Can you tell me _______ ?
—He is a doctor．
A. who is he B. who he is C．what does he do D. what he does
【单选题】
( ) 26.With help from a Mr. H, you can__________.
A. stop wearing your watch B. get new books and objects
C. finish your homework on time D. know when parents or teachers are near
【单选题】
( ) 27. A PENGO WATCH CONTROL can help you to ______________.
A. repair your TV B. put away your books and objects
C. become a James Bond D. get a daily weather report
【单选题】
( ) 28. You can get your Mr. H for___________.
A. $299 B. $499 C. $199 D. $99
【单选题】
( ) 29. When was canned food invented?
A. In 1870. B. In 1810. C. In 1902. D. In 1926.
【单选题】
( ) 30. After the trip to the Arctic, Clarence Birdseye invented ____________.
A. canned food B. can openers
C. frozen food D. air conditioning
【单选题】
( ) 31. Changes in weather _____________ in Willis Carrier's company.
A. helped to keep food B. made rooms comfortable
C. caused health problems D. hurt printing paper
【单选题】
( ) 32. According to the passage, which of the following may lead to inventions?
A. People's needs. B. Public support.
C. Modern technology. D. Practical suggestions.
【单选题】
( ) 33. What is the writer's main purpose（目的）in writing this passage？
A．To tell the readers his life story．
B．To tell people what kind of person his father was．
C．To tell the readers what present he got from his father．
D． To let people know how poor he was．
【单选题】
( ) 34. Why did the father not ask his son not to do this and do that？
A．Because he felt quite confident of his son．
B．Because he was born from a poor family．
C．Because he was a man of few words．
D．Because he didn't want to be much too strict with his son．
【单选题】
( ) 35. What would someone learn from this passage？
A．How to live by oneself． B．How to stand on one's own feet．
C．What a good father should do． D．What the self-important is like．
【单选题】
( ) 36. What may be the proper Chinese for the underlined part in the passage？
A．闲暇时光 B．学费 C．精神空虚 D．经济不足
【单选题】
( ) 37. The Chinese Yellow Sea Wetlands are in the _______ of China．
A．south B．east C．west D．north
【单选题】
( ) 38. Usually the weather in the wetlands is _______．
A．hot B．pleasant C．cold D．dry
【单选题】
( ) 39. The World Wetlands Day is on _______．
A．February 2 B．June 25 C．April 22 D．March
【单选题】
( ) 40. We must protect wetlands because _______．
A．they are home for wildlife B．they can prevent flood
C．they can offer food to the animals and birds D．all of the above
【单选题】
) 1. —Is it far from here to the bank?
—Not very, only________．
A. 20 minute’s walk B. 20 minutes walk
C. 20 minutes’ walk D. 20 minutes’ walks
【单选题】
2. — After discussing, the students ________ some good ideas to work on the project.
— Thats great!
A. put up B. set up C. caught up with D. came up with
【单选题】
3. Yesterday Tommy walked past my table and ______ my bowls and dishes.
He should be careful next time.
A. knocked off B. took off C. showed off D. turned off
【单选题】
4.We don’t have enough nurses to look after patients．At least ___ nurses are needed．
A. ten another B. more ten C. another ten D. other ten
【单选题】
5. — Zhao Rui, it’s said that many famous singers will come to Yangzhou on April 18th. How about watching the evening show there?
—________! Let’s ask Huang Tao to go with us.
A. Best wishes B. Sounds great C. Good luck D. That’s OK
【单选题】
6.—Hello! This is Henry Speaking．I’d like to speak to your father．
—Sorry, he has Shanghai．
A. been in B. been to C. come to D. gone to
【单选题】
7. — It’s difficult for the village children to cross the river for school．
— I think a bridge ______ over the river．
A. was built B. is being built C. has been built D. should be built
【单选题】
8. —Where would you like to go, Jinan or Qufu?
— ．I only want to go to Qingdao．
A. Each B. Either C. Neither D. All
【单选题】
9 — The documentary A Bite Of China II is quite popular around China recently. How do you like it? ______.
A. I think so B. Pretty good C. Its my pleasure D. All right
【单选题】
10. There are three English-books on the shelf, but ______ of them is mine.
A. both B. neither C.all D. none
【单选题】
11. When the parents arrived at the hall, the students _______ their projects.
A. have finish B. finished C. had finished D. are finishing
【单选题】
12. This week, the _______ seems to change every day: one day is hot; the next day is cold.
A. time B. weather C. season D. way
【单选题】
13. He never does his work _______ Mary.
A. as careful as B. so careful as C. carefully as D. as carefully
【单选题】
14. — Can he jump high?
— Yes, he ______. He is a good high jumper.
A. must B. need C. can D. shall
