课程名称︰生物化学 课程性质︰化学系五选三必修 课程教师︰陈平 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰2012/06/06 考试时限（分钟）：60mins 是否需发放奖励金：是 （如未明确表示，则不予发放） Exam7 223 U0860, 6/62012 Name:____(1pt) 学号:____(1pt) (Total 113 pt, maximum 105 pts) I. Multiple Choice. There is only one correct answer for each question (18x3pts,54 pts) __1.Olycoproteins are normally A) found on membranes. B) secreted as etracellular proteins. C) found inside some organelles. D) A and B. E) all of the above. __2. Regarding the N-glycosyl donor for N-linked glycosylation A) the glycosyl donor is UDP-glucose B) the glycosyl donor is assembled on the lumen face of tht ER C) the glycosyl donor is assembled on the cytoplasmic face of the ER D) the glycosyl donor is assembled on the cytoplasmic and lumen face of the ER E) A and D __3.This is responsible for directing elastase through the ER membrane. A) signal sequence B) carbohydrate C) ribosomes D) all of the above E) none of the above __4.Carbohydrate processing in the Golgi complex is called A) core glycosylation. B) terminal glycosylation. C) glycosylation modification. D) all of the above. F) none of the above. __5.Organelle(s) that degrade and recycle cellular components. A) lysosomes B) endoplasmic reticulum C) Golgi complex D) A and B E) none of the above __6. Glycoforms refers to 4) a single protein type that can have forms that vary in glycosylation B) glycoproteins from the same gene family. C) a common core of sugars that can be found on many different proteins. D) all of the above. E) none of the above. __7. Which of the following statement(s) is (are) true? A) lectins can bind the carbohydrates on glycoproteins and other macromolecules B) lectins can promote cell-cell interaction C) lectins are found animals, plants, and microorganisms D) A and B E) all of the above __8.Regarding the protein folding in the endoplasmic reticulum (ER)? A) for properly folded proteins, glucose is cleaved and the protein is sent to the Golgi B) a glucose residue is added to improperly folded proteins C) glucose residues allow chaperones to bind proteins for assisted folding D) A and B E) all of the above __9.How do some viruses gain entry into specific cells? A) by attaching to ion channels B) by cleaving the glycosidic bonds and altering protein shapes C) by binding to glycoproteins on the cell surface that are unique to specific cells D) all of the above E) none of the above __10.Which of the following membranes would he the most fluid-like (lowest Tm)? A) a bilayer made of lipids with saturated 16 carbon-fatty acids B) a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids C) a bilayer made of lipids with saturated 18 carbon-fatty acids D) a bilayer made of lipids with polyunsaturated 18 carbon-fatty acids E) All of the above are equivalent in fluidity. __11. Carbohydrates attached to the lipid are always positioned on A) the inside center of the bilayer. B) the intracellular side of the membrane. C) the extracellular side of the membrane. D) A and B. E) A and C. __12. Which of the following statements about membrane lipids is true? A) Phophatidylcholine is a sphingolipid. B) Glycerophospholipids contain fatty acids linked to glycerol through amide bonds. C) Some sphingolipids include oligosaccharides in their structure. D) Glycerophospholipids are found only in the membranes of plant cells. E) None of the above. __13.Which of the following is NOT true of cholesterol? A) Cholesterol is commonly found in mammals. B) Cholesterol has a structure that includes four fused rings. C) Cholesterol is commonly found in bacterial membranes. D) Cholesterol is a precursor of steroid hormones. E) Cholesterol is more common in plasma membranes than in intracellular membranes (mitochondria. lysosomes, etc.). __14. Which is the proper order of permeability of molecules across a membrane, from the most permeable to the least? A) water, glucose, urea, sodium ion B) water, indole, glucose, sodium ion C) wrater, indole, sodium ion, glucose D) indole, glucose, urea, sodium ion E) indole, water, glucose, sodium ion __15. The most common α-helical motif found in membrane spanning proteins is A) α-helicals of nonpolar amino acids that pass through the membrane, B) α-helicals of charged amino acids that form channels via extensive hydrogen bonding. C) triple helix ofα-helicals. D) α-helix-turn-helix arrangement of the peptide strands. E) none of the above. __16. The low incidence of protein or lipid flip-flop in a membrane preserves A) membrane fluidity. B) membrane melting temperatures. C) membrane asymmetry. D) all of the above. E) none of the above. __ 17. Which of the following might be found in a protein destined for the nucleus? A) Lys-Lys-Lys-Arg-Lys 13) Gly-Phe-Gly-Phe-Gly C) Ile-Met-Leu-Leu-Val D) all of the above E) none of the above __18. Inside the cell, the concentration of Na+ and K+ are A) [Na+] > [K+] B) [Na+] = [K+] C) [Na+] < [K+] II. Fill in the blanks (6x3 pts; 18 pts) 1. Name the two different sugars that are part of the core pentasaccharide in N- linked oligosaccharides. a)__ b)__ 2. Inhibitors against which enzyme have potential as anti-influenza agents? 3. How many molecules thick are membranes? 4. What technique is used to measure, lipid movement in a bilayer? 5. Please rank the following lipoproteins from high to low in content of triacyglycerol (triglyceride) A. Chylomicrons B. VLDL C. LDL D. HDL III. Short questions (9 pts). I. How do the archaeal membranes differ from bacteria and eukaryote membranes? (6 pts) 2. Why is prostaglandin H2 synthase-1 partially embedded in the membrane? (3 pts) IV. Structure drawing with stereochemistry (30 pts) 1. Draw the structure of DPPS (1,2- dipalmitoyl-sn-glycero-3-phosphoserine or 1,2-dipalmitoyl-phosphatidyserine). (8pts) 2. Draw the structure of DOPS (1,2- dioleoyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-phosphatidycholine). (8pts) 3.Draw the structure of sphingomyelin with the stearoyl group attached (8pt) 4.Draw the structure of cholesterol (6pts) ANS I.EDABA AEECB CCCBA CAC II. 1. mannose GlcNAc 2. neuraminidase 3.2 4.FRAD 5.A>B>C>D III. 1. (1) invert stereochemistry (2) ether bond instead of ester bond (3) branch methyl groups 2.better access to substrate --

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