中大生物化学试题答案与评分标准(2005秋季,A卷).docVIP

生物化学I（2005年秋季学期, A卷） 专业(班级)： 姓名： 学号： 阅卷教师： 题号 一 二 三 四 五 合计 分数 《中山大学授予学士学位工作细则》第六条：“考试作弊不授予学士学位”。 1. With regard to amino acids, which statement is false? A) Amino acids can act as proton donors and acceptors. B) All amino acids discovered in organism are L enantiomers. C) An L amino acid can be Dextrorotary. D) Non-standard amino acids can be found in the hydrolysis product of a protein. 2. In a highly acidic solution, pH = 1.3, the dominant form of glycine is: A) NH2-CH2-COOH；B) NH3+-CH2-COOH；C) NH2-CH2-CO–；D) NH3+-CH2-COO–. 3. In the isoelectric form of a tetrapeptide: A) The amino and carboxyl termini are not charged. B) Two internal amino acids of the tetrapeptide cannot have ionizable R groups. C) The total net charge is zero. D) Only the amino and carboxyl termini contribute charge. 4. Which would elute first from a gel-exclusion chromatographic column? A) a negatively charged protein of MW=40,000 B) a positively charged protein of MW=40,000 C) a protein at its isoelectric point of MW=30,000 D) a polysaccharide of MW=100,000 5. In an aqueous solution, protein conformation is determined by two major factors. One is the formation of the maximum number of hydrogen bonds. The other is the: A) formation of the maximum number of hydrophilic interactions. B) maximization of ionic interactions. C) minimization of entropy by forming a water solvent shell around the protein. D) placement of all hydrophobic amino acid residues within the interior of the protein. 6. You can destabilize a duplex DNA molecule in an aqueous solution by A) Decreasing the concentration of salt. B) Decreasing the concentration of organic solvents. C) Adjusting the pH to a value near 7. D) Adding a detergent. 7. With regard to DNA, which statement is false? A) Triple helix and tetraplex tend to appear at sites where replication, recombination or transcription is initiated or regulate