following statements is true about the distribution of K+?( ) a. K+ must be at equilibrium across the cell membrane b. K+ cannot be at equilibrium across the membrane
c. There cannot be a membrane potential under these conditions More information is needed to determine whether K+ is at equilibrium
7. Which mutant form of ras is likely to cause malignancy?( ) a. ras that cannot hydrolyze GTP b.ras that cannot bind to GTP c. ras that cannot bind to Grb2 or Sos d. ras that cannot bind to Raf
8. The hormone glucagon stimulates the breakdown of stored glycogen in liver and muscle cells by the following enzymes. Which is the first enzyme that must be activated?( ) a. Protein kinase A b. Phosphorylase kinase c. Glycogen phosphorylase d. Protein phosphatase e. Protein phosphatase inhibitor-1
9. A cancer-causing gene makes G protein permanently bind to GTP, this results in( ). a. Continual production of cAMP. b. Continual production of GDP. c. Inhibition of cGMP production. d. Inhibition of adenylyl cyclase. e. None of the above
10. Which one of the following is not part of a prokaryotic ribosome?( ) a. A 30S subunit consisting of 16S rRNA b. A 50S subunit consisting of 23S and 5S rRNA c. A 30S subunit consisting of 21 proteins d. A 40S subunit consisting of 18S rRNA e. None of the above
11. Which one of the following was used to determine the structure of the DNA molecule?( ) a. Transmission electron microscope b. Scanning electron microscope c. Differential centrifugatioin d. X-ray crystallography e. None of the above
12. You stain membrane proteins with a fluorescent-labeled antibody and notice the membrane is evenly stained. After a few hours, all of the fluorescence is at one end of a cell. You can conclude that( ).
a. Lipids flip-flop in the membrane. b. Proteins move laterally in the membrane. c. The fluorescent dye was bleached. d. Proteins act as transporters. e. All of the above
13. You have a preparation of ghosts and need to collect only the right-side out ghosts. You decide you can trap the right-side out ghosts in an affinity column packed with( ) a. SDS. b. A carbohydrate-binding molecule.
c. A protein-binding antibody. d. A serine-binding molecule. e. None of the above
14. All of the following individuals contributed to cell theory except( ) a. Robert Hooke. b. Matthias Schleiden. c. Theodor Schwann. d. Rudolf Virchow.
15. The addition of a peptide with an RGD sequence would probably ? the binding of cultured cells to a fibronectin coated dish.( ) a. enhance b. inhibit
c. have no effect on d. none of the above
16. 适于观察细胞表面及断面超微结构三维图像的仪器是( ) a．普通光镜 b．荧光显微镜 c．相差光镜 d．扫描电镜 e．透射电镜 17. 红细胞中O2与CO2交换作用主要依靠( )
a．血影蛋白 b．血型糖蛋白 c. 带Ⅲ蛋白 d．锚定蛋白 e. 肌动蛋白
18. 能与胞外信号特异识别和结合，介导胞内信使生成，引起细胞产生效应的是( ) A．carrier protein B．channel protein C．receptor D．1iand E．enzyme 19. 下列连接方式中属于与中间纤维相连的锚定连接的是( )。 a．粘合带； b．粘合斑； c．桥粒； d．紧密连接。
20. 带电的离子之所以不能自由通过质膜,其原因是( ) a.膜的孔径不够大; b.膜的电性与离子电性相斥; c.带电的离子聚集成团;
d.带电离子通常与水形成水性外壳,以至于体积过大。
四、简答题(每题4分， 选做5题，共20分)
1. 基因敲除(knockout)实验中有哪些关键环节影响试验的成败？
2. 真核生物与原核生物的rRNA基因在组织结构、转录和加工中有什么 差异？
3. G protein-linked receptors activate heterotrimeric G proteins through inter-actions between the receptor and the Gb¡ subunit. Upon binding to the receptor, the Gb¡ subunit then catalyzes GDP/GTP exchange by the Ga subunit. How is this similar to the activation of Ras by a receptor tyrosine kinase?
如何理解“被动运输是减少细胞与周围环境的差别,而主动运输则是 努力创造差别,维持生命的活力”?
5. 1981年，Thomas Cech和他的同事在世界上首次发现核酶，并获得了支持这一发现的实验证据。从他们的发现中你有何感想？
6. 为什么说水是细胞中优良的热缓冲体系？
五、实验设计与分析。(简要说明，不需详细步骤。每小题5分,共10分)。
1. Some integral membrane enzymes depend upon the lipids in their microenvironment not only for scaffolding, but for enzymatic activity. The Na+-K+ ATPase is one example. Please design an experiment to test the influence of membrane fluidity on the velocity of the Na+-K+ ATPase.
2. Describe the experimental approach used to identify functional domains of G-protein coupled receptors.
六、分析、计算与思考(20分) 1. 分析题（任选1题，5分）
(1) Hypertension, or high blood pressure, is often seen in elderly people. A typical prescription to reduce a patient's blood pressure includes compounds called beta-blockers, which block b-adrenergic receptors through-out the body. These receptors bind epinephrine, thereby activating a cellular response. Why do you think beta-blockers are effective in reducing blood pressure?
(2)“解铃还需系铃人”这句谚语在细胞活动中能找到对应的故事吗？ 请说明。
2. 计算与思考（5分）
Assume you were given a mixture consisting of one molecule each of all possible sequences of a smallish protein of molecular weight 4800. How big a container would you need to hold this sample? Assume that the average molecular weight of an amino acid is 120.
What does this calculation tell you about the fraction of possible proteins that are currently in use by living organisms {the average molecular weight of proteins is about 30,000}?
2. 综合思考(10分, 按答题最多者计算每题得分)
(1) Compare and contrast the extracellular matrix (ECM) of animal cells with the walls around plant cells.
(2) 举例（3～5个）说明研究方法的突破对细胞生物学发展的推动作用。
(3) Heating of calf type I collagen fibers to 450C denatures the triple helices and separates the three chains from each other. Collagen that has been treated in this way does not renature to form a normal collagen triple helix. Why?
(4) Hypertension, or high blood pressure, is often seen in elderly people. A typical prescription to reduce a patient's blood pressure includes compounds called beta-blockers, which block b-adrenergic receptors through-out the body. These receptors bind epinephrine, thereby activating a cellular response. Why do you think beta-blockers are effective in reducing blood pressure? 试题三参考答案
一、填空题(每空0.5分，共10分) 1. 水分间的氢键 能够吸收较多的热能。 2. Arg-Gly-Asp。 3. _Calmodulin_ i 4. __Ligand.
5. _IP3_ ， DAG .
6. _Adenylyl cyclase_ ，_phosphodiesterase_ 7.鸟苷酸环化酶。 8. 粘着斑
9. K+-Na+泵， H+泵。
10. 节省了遗传信息量，减轻了核的负担。 11. 答：体积与表面积; 重要分子在细胞内的浓度 12. 10， 2 13.非钙
二、判断题(若是正确的标√号， 错误的标×号，并做简要说明。每题 1分，共20分)
1.答：错误，短杆菌肽A形成离子通道。 2. (√)
3. ×,有两种情况,另一种情况是通过糖与脂的共价连接进行锚定 4. ( × ) 5．答：正确。
6.答: 错误, Ⅱ型内含子的剪接不形成剪接体。
7.答: 错误, 是RNA聚合酶Ⅲ转录的, 使用的是内部启动子。 8.（√） 9.（√）
10. Answer:F; the direction of movement depends on both the concentration gradient and the membrane potential, so facilitated diffusion can occur from a compartment of lower concentration to a compartment of higher concentration if the membrane potential is in the right direction and of sufficient magnitude.
11.Answer:F; hydrolysis of high-energy phosphate bonds is a common means of driving active transport, but so is an ion gradient, as in sodium-driven cotransport of sugars and amino acids
into cells.
12.Answer:F; if the sodium-potassium pump is inhibited, the sodium gradient necessary for sodium-driven glucose uptake cannot be maintained and cotransport will decrease or even cease as the sodium gradient collapses.
13. Answer:False. Tight junctions provide molecule-tight seals between cells. 14.Answer.False. Gap junctions are communicating junctions. 15. Answer.True 16. Answer.True
17. 答：错误，除了水解酶的活性外，还有其他酶的活性，如磷酸酶活性。 18．答：错误，应是5.8S。 19．答：错误，结合水只占4～5%。 20. 答：错误，电镜要用电子染色。
三、选择题(请将正确答案的代号填入括号，每题1分，共20分) 1. 答：b. 正确 2. 答：c. 3. 答: c 4. 答: d 5.答: b 6. 答:d 7. 答:a 8. 答:a 9. 答:a 10. 答:d 11. 答:d 12. 答:b 13. 答:b 14. 答:a 15. 答:c 16．答:d 17．答:c 18. 答:c 19. 答:c 20. 答:d
四、简答题(每题4分， 选做5题，共20分)
1.答：①基因突变；②受体细胞—胚胎干细胞；选择标记
2. 答：①真核生物的18S rRNA-5.8S rRNA-28S rRNA串联在一起；原核生物的16S rRNA-5SrRNA-23S rRNA串联在一起；②真核生物的18S rRNA-5.8S rRNA-28S rRNA物中不含tRNA基因；原核生物的16S rRNA-5SrRNA-23S rRNA转录物中有tRNA基因的转录产物。
3. Answer:The activation of Ras requires the assistance of another protein called SOS. Upon binding