1. 决定红细胞ABO血型的物质是糖脂，它由脂肪酸和寡糖素链组成。A型血糖脂上的寡糖链较O型多一个 ；B型血仅多一个 。
2. 根据题意, 将与A、B、C、D相对应的词用连线连起来:
Cells communicate in ways that are analogous to human communication. Decide which of the following forms of human communication are analogous to autocrine, paracrine, endocrine, and synaptic signaling by cells. A. A telephone conversation: autocrine
B. Talking to people at a cocktail party: endocrine C. A radio announcement: synaptic signaling D. Talking to yourself : paracrine
3. What is the major factor that determines the limit of resolution of a light microscope? 4. 编码载脂蛋白B的基因在肠组织中转录成mRNA后,第2153位的C被 形成U,使CAA密码转变成终止密码UAA, 使翻译提前终止。
5. 是细胞外基质的受体蛋白。在结构上，它们是异二聚体，。这种跨膜蛋白的细胞外部分有一个球形的头部，可与细胞外基质蛋白结合，而细胞质结构域则可与 相结合。
二、判断以下各题是否正确, 若正确, 用T表示, 不正确用F表示,并做简要说明。 (每题1分，共10分) 1. Both the GTP-bound a subunits and nucleotide-free b¡ complexes, but not GDP-bound, fully assembled G proteins, activate other molecules downstream of G-protein-linked receptors. 答:
2. The density of water is less than the density of ice. 答:
3. Water has a high specific heat. 答:
4. There is no fundamental distinction between signaling molecules that bind to cell-surface receptors and those that bind to intracellular receptors. 答:
5. How is it that different cells can respond in different ways to exactly the same signaling molecule even when they have identical receptors? 答:
6. Protein kinase A itself is different in different cell types, which explains why the effects of cyclic AMP vary depending on the target cell. 答:
7. It is thought that extracellular ligand binding to a receptor tyrosine kinase activates the intracellular catalytic domain by propagating a conformational change across the lipid bilayer through the single transmembrane a helix. 答:
8. Atrial natriuretic peptides(心钠肽) bind to a receptor that activates
a G protein,which in turn activates guanylyl cyclase(鸟苷环化酶) to produce cyclic GMP which then activates a cyclic GMP-dependent protein kinase (PKG). 答:
9. Because prokaryotic cells have neither mitochondria nor chloroplasts, they cannot carry out either ATP synthesis or photosynthesis.
答:
10．电镜的波长与电压有关，电压越高，波长越短，分辨率越高。 答:
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. Which one of the following is incorrect for the biogenesis of eukaryotic ribosomes?( ) a. 25-50% of the pre-rRNA is degraded b. Pre-rRNA binds to ribosomal protein
c. Pre-rRNA is cut to form three classes of rRNA d. Pre-rRNA is methylated
e. The rRNA gene for the 40S subunit is transcribed separately
The 5S rRNA differs from the other cellular rRNAs in which of the following ways? ( )
a. The genes are located outside the nucleolus(核仁). b. The genes are transcribed by RNA polymerase III.
c. The promoter region of the 5S rRNA gene is internal to the gene. d. all of the above 3． 钙泵的作用主要是( )。
a．降低细胞质中Ca2+的浓度； b．提高细胞质中Ca2+的浓度； c．降低内质网中Ca2+的浓度； d．降低线粒体中Ca2+的浓度
4. Plant guard cells(保卫细胞) have a higher [C1-] than the outside environment. The most likely explanation for this is( ). a. Water leaves the cell by osmosis.
b. C1- is diffusing through transmembrane channels. c. C1- diffusion is aided by a mobile carrier. d. An active transport symport transports C1-/H+. e. None of the above
5. The hormone glucagons(胰高血糖素) 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 6. 在下列组织中, 紧密连接特别重要的有( ) a. Stomach(胃) and kidneys b. Smooth muscle c. Heart muscle
d. Intestinal epithelial tissue(肠表皮组织)
7. Which one of the following was used to determine the structure of the DNA molecule? ( )
a. Transmission(透射) electron microscope b. Scanning electron microscope
c. Differential centrifugatioin(差速离心)
d. X-ray crystallography 8. A eukaryotic cell has( )
a. One copy of each ribosomal transcription unit. b. Thousands of copies of the 5S rRNA gene.
c. Two copies of each gene for rRNA and ribosomal proteins.
d. Two copies of each gene for rRNA and one copy of each ribosomal protein gene.
9. All of the following are true about antisense RNA except ( ) a. Is complementary to mRNA. b. Forms double-stranded RNA. c. Joins with the 30S subunit. d. Inhibits protein synthesis.
10. Developing frog embryos treated with anti-fibronectin antibodies a. Develop normally.( ) b. Stop cell division.
c. Have abnormal cell migration(迁移). d. Don't exhibit action potentials.
11．肌动蛋白纤维对于黏着斑就像( )对于半桥粒。 a．肌球蛋白纤维 b．角蛋白纤维 c．微丝 d．钙粘着蛋白 12．配体(ligand)是（ ）。 a．酶与底物共价结合的活性位点； b．酶与底物非共价结合的活性位点；
c．对于一个与蛋白质以共价形式相作用的小分子的普遍称呼； d．对于一个与蛋白质以非共价形式相作用的小分子的普遍称呼； e．一个缺乏酶活性的球蛋白
13．膜胆固醇的组成与质膜的性质、功能有着密切的关系,（ ） a．胆固醇可防止膜磷脂氧化；
b．正常细胞恶变过程中，胆固醇/磷脂增加； c．胆固醇/磷脂下降，细胞电泳迁移率减少；
d．在质膜相变温度以下，增加胆固醇，可以提高膜的流动性
14．用抗纤连蛋白的抗体注射胚体，发现在神经系统发育过程中神经嵴细胞的迁移受到抑制。这些实验说明：( )
a．神经嵴发育包括抗体基因的表达； b．发育中的神经无需合成纤连蛋白；
c．纤连蛋白/抗体复合物形成神经细胞的迁移途径； d．胚胎中的神经元在移动过程中必须与纤连蛋白暂时结合 15．当胰岛素与其受体酪氨酸激酶结合后，随后发生的事件是( )。 a．IRS的结合→具有SH2区域的蛋白质的磷酸化→效应； b．与具有SH2区域的蛋白质结合→IRS的磷酸化→效应；
c．自磷酸化并将IRS磷酸化→与具有SH2区域的蛋白质结合→效应； d．自磷酸化并与IRS结合→将具有SH2区域的蛋白质磷酸化→效应
四、简答题(每题4分，共40分)
What functional roles do the ECM (细胞外基质)and cell wall share in common?
2. Discuss the following analogy(相似): “The differences between transporting a ligand by a channel or a carrier protein are like the differences between crossing a river by a bridge or a ferry(摆渡).\3. EGTA chelates(螯合) Ca2+ with high affinity and specificity. How would microinjection(微注射) of EGTA affect glucagon-triggered breakdown of glycogen (糖原) in liver?
4. The basic structure of biological membranes is determined by the lipid
bilayer, but their specific functions are carried out largely by proteins. Explain your answer. 5. Why does a red blood cell membrane need proteins?
6. Describe the different methods that cells use to restrict proteins to specific regions of the plasma membrane. Is a membrane with many anchored proteins still fluid?
7. Transport by carrier proteins can be either active or passive, whereas transport by channel proteins is always passive. Explain your answer. 8. The signaling mechanisms used by a steroid-hormone(固醇激素) receptor
and by an ion-channel-linked receptor have very few components(组分). Can either mechanism lead to an amplification of the initial signal? If so, how?
9. Should RGS (regulator of G protein signaling) proteins be classified
as GEFs (guanine nucleotide exchange factors) or GAPs (GTPase activating proteins)? Explain what role this activity plays in modulating G-protein-mediated responses in animals and yeasts. 10. How is an IP3-triggered Ca2+ response terminated?
五、简述第二信使cAMP的发现及生成的实验证明(20分)。
六、分析与思考(任选一题, 20分)
1. Why do you suppose that phosphorylation/dephosphorylation, plays such a prominent role in switching proteins on and off in signaling pathways?
2. The Ras protein functions as a molecular switch that is set to its on state by a guanine-nucleotide exchange factor (GEF) that causes it to bind GTP. A GTPase-activating protein (GAP) resets the switch to the off state by inducing Ras to hydrolyze its bound GTP to GDP much more rapidly than in the absence of the GAP. Thus Ras works like a light switch that one person turns on and another turns off. In a cell line that lacks the Ras-specific GAP, what abnormalities would you expect to find in the way Ras activity responds to extracellular signals?
附加题(每题3分):
Proteins that span a membrane as an a helix have a characteristic
structure in the region of the bilayer. Which of the three 20-amino acid sequences listed below is the most likely candidate for such a transmembrane segment? Explain the reasons for your choice. A. I T L I Y F G V M A G V I G T I L L I S
B. I T P I Y F G P M A G V I G T P L L I S C. I T E I Y F G R M A G V I G T D L L I S
2. Why are a helices more common than b barrels in transmembrane proteins?
3. Through the exchange of small metabolites and ions, gap junctions provide metabolic and electrical coupling between cells. Why, then, do you suppose that neurons communicate primarily through synapses (突触)rather than through gap junctions?
试题五答案
一、填空题(每空0.5分，共5分) 1. N-乙酰半乳糖胺残基，半乳糖残基 2.
A. 电话交谈: 自分泌 B. 集会演讲 内分泌 C.无线电广播 突触信号传导 D. 自言自语 旁分泌 3. 波长 4. 脱氨
5． 整联蛋白 肌动蛋白纤维
二、判断以下各题是否正确, 若正确, 用T表示, 不正确用F表示,并做简要说明。 (每题1分，共10分)
1. 正确。bg复合物能够激活离子通道, 结合有GTP的亚基能够激活酶。 2. 错误。冰的密度比水低。这样就保证冰能够漂浮在水的表面, 并在温度升高超 过冰点时化冰。
3. 正确。高比热意味着需要较多的热才能升高温度。这就有效地缓冲了细胞对周围环境温度而保持细胞温度的稳定。
4. 错误。与细胞表面受体结合的信号分子不必跨过质膜, 因此, 此类信号分子可 大可小, 疏水或亲水。但与细胞内受体结合的信号分子必须足够小和疏水。
5. 主要是不同的细胞对信号反应的内部机制不同。既便是反应途径相同, 不同的细胞也会表达不同的蛋白质进行应对。
6. 错误。是因为不同细胞中PKA的底物不同, 而不是蛋白激酶A的不同。 7. 错误。配体与受体酪氨酸激酶的结合引起二聚体的装配。任何受体进行自磷酸 化, 从而启动细胞内的信号级联反应。在某些情况下, 如胰岛素受体, 通过细 胞外的两个受体形成二聚体, 然后通过两个α螺旋进行构型的变化。
8. 错误。心钠肽直接与受体鸟苷环化酶结合, 将之激活, 并由激活的鸟苷环化酶 产生cGMP, 再由cGMP激活PKG。
9. 错误。原核细胞同样能进行ATP的合成和光合作用。只不过不是通过细胞内的 区室, 而是通过中膜体之类的结构。 10．正确
三、选择题(请将正确答案的代号填入括号，每题1分，共15分)