biochemistry 2008B卷 answer.doc

姓名 学号 学院 专业 座位号 ( 密 封 线 内 不 答 题 )密封线线_ _ 诚信应考,考试作弊将带来严重后果！ 华南理工大学期末考试Biochemistry试卷 B注意事项：1. 考前请将密封线内各项信息填写清楚； 2. 所有答案请直接答在试卷上(或答题纸上)； 3考试形式：闭卷； 4. 本试卷共五大题，满分100分，考试时间120分钟。题 号一二三四五总分得 分评卷人1、Translate following biochemistry terms from English to Chinese: (0.5 point each, total 5 points)replication fork 复制叉 molecular chaperones 分子伴侣purine 嘌呤nitrogen fixation 固氮transition state过渡态catabolic pathway 分解代谢citric acid cycle柠檬酸循环ketone body 酮体Okazaki fragment冈崎片段transamination 转氨基反应2. Multiple choice(s) based on the question. (1) In the following formula, which one describe-D-glucopyranose？(2 points)BA DC Answer:_A_(2) Which of the following compounds directly provide atoms to form the purine ring? (3 points)A. Aspartate.B. Carbamoyl phosphate.C. Glutamine.D. Glycine.E. CO2.F. N5,N10-methylenetetrahydrofolate.G. N10-formyltetrahydrofolate.H. NH4+.Answer:_A CDEG_(3) The AAUAAA sequence on a RNA molecule marks (2 points)A. The site where ribosomes bind to initiate polypeptide synthesis.B. The site where transcription stops.C. The site near which the primary transcript is cleaved and a poly (A) sequence is added.D. The site where the release factor will bind to end polypeptide synthesis.E. The site where polyribonucleotide phosphorylase will add a stretch of random sequences.Answer:_C_3. Indicate whether each of the following statements about prokaryotic translation is true (T) or false (F). (1 point each, total 7 points)( T ) (1) An aminoacyl-tRNA synthetase catalyzes formation of an ester bond. ( F ) (2) An mRNA molecule cannot be used to direct protein synthesis until it has been completely transcribed. ( F ) (3) The positioning of fMet-tRNA on the A site defines the reading frame. ( T ) (4) Incoming aminoacyl-tRNA are first bound to the A site. ( T ) (5) Formation of the 70S initiation complex requires an input of energy. ( F) (6) The carboxyl group of the amino acid on the aminoacyl-tRNA is transferred to the amino group of a peptidyl-tRNA. ( T ) (7) Release factors cause the peptidyl transferase activity of the ribosome to use H2O as a substrate. 4、Please answer the following question, total 81 points.(1) Give the one-letter and three letter abbreviations for the following amino acids and indicate which are polar, nonpolar, acidic or basic (1.5 point each).Aspartic acid Asp, D, acidPhenylalanine Phe, F, nonpolarSerinie Ser, S, polarLeucine Leu, L, nonpolarLysine Lys, K, basicGlutamine Gln, Q, polar(2). Glutamic acid has the following pKa value:-COOH PKa=2.19，-NH3+ pKa=9.67 and R group pKa=4.25. Write equatations for the inonic disociatins of Glutamic acid . What is the isoelectric point of Glutamic acid? (6 points)pI= (2.19 + 4.25)/2=3.22 (3). List the six major enzyme categories based on IUB classification of enzymes (6 points)Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases , Ligases (4)(9 points) what is the secondary, tertiary and quaternary structure of protein? And where does their structural information come from?I. the secondary structure refers to the regular, recurring arrangements of adjacent residues resulting mainly from hydrogen bonding between backbone groupsII. the tertiary structure refers to the spatial relationship among all amino acid residues in a polypeptide chain, that is, the complete three-dimensional structure.III. the quaternary structure refers to the spatial arrangements of each subunit in a multi-subunits protein, including nature of their contact.IV. All of the information necessary for folding the peptide chain into its “native” structure is contained in the amino acid sequence of the peptide.(5) (9 points) how does transport occur across biological Membrane?I. Passive transportSimple diffusion: Each solute, propelled by random molecular motion, moves down its concentration gradient.Facilitated diffusion: The transport of certain large or charged molecules occurs through special channels or carriers.II. active transportCells accumulate molecules against a concentration gradient and this process requires energy.Primary active transportEnergy is supplied with ATP.Secondary active transportConcentration gradients generated by primary active transport are harnessed to move substances across membrane. (6) (9 points) Carbonic anhydrase catalyzes the hydration of CO2: CO2 + H2O H2CO3The Km of carbonic anhydrase for CO2 is 12 mM. Carbonic anhydrase gave an initial velocity v = 4.5 mol H2CO3 formed /mL.sec when CO2= 36mM. Thena. What is Vmax for this enzyme:b. Assuming 5 x 10 9 M of enzyme were used in this experiment, what is Kcat for this enzyme?c. What is the catalytic efficiency of this enzyme?a. Vmax = v(Km + S)/S = 4.5 x 10-3 (12 +36) /36 = 6 x 10-3M/sb. Kcat = Vmax/Et = 6 x 10-3/ 5 x10 9 = 1.2 x 10 -6/sc. Kcat/Km = 1.2 x 10 -6/12 x 10-3 = 1x 108M-1S-1(7) (9 points) Caculate the approximate number of ATP molecules that can be obtained from the oxidation of oleic acid (18 carbon mono-unsaturated fatty acid) to CO2 and water. Reaction ATP yieldActivation of oleic acid, -2Oxidation of 9 Acety-CoA, 9 x 12 =108(9 x 10 =90)Oxidation of 7 FADH2 7 x 2 = 14(7 x 1.5= 10.5)Oxidation of 8 NADH 8 x 3 = 24(8 x 2.5= 20)Net: 144(118.5)(8) (6 points) in an erythrocyte undergoing glycolysis, what would be the effect of a sudden increase in the concentration ofATP? (inhibit )AMP? (stimulate )Fructose-1,6-bisphosphate? (stimulate)Fructose-2,6-bisphosphate? (stimulate)Citrate? (inhibit)Glucose-6-phosphate? (stimulate)(9) (8 points) what is the genetic code, and what role does it play in gene expression? List and describe properties of genetic code. The genetic code is the code of bases that specific the sequence of amino acids in a protein. The genetic code is a triplet code. 64 three-letter codons are available to specify 20 amino acids found in proteins.61 are used for amino acids, and 3 are stop codons.Properties: Degenerate; Specific; Nonoverlapping and without punctuati