清华大学2005年生物化学期末试卷.docVIP

清华大学本科生考试试题专用纸考试课程 Biochemistry II 2005 年 1 月 15 日 说明：1.答案可能是一个或多个请正确答案填在适当的横线处； 2.的分数标在题目后面. 本卷满分为100 1. Which compound links glycolysis, nucleotide synthesis, and glycogen synthesis? acetyl-CoA oxaloacetate citrate glucose 6-phosphate glycerol 3-phosphate Answer(s): D 2. You have discovered a compound that inhibits fumarase. How many moles of ATP would you expect to be generated from one mole of acetyl-CoA in the presence of this inhibitor? 5 6 6.5 7.5 No ATP would form under these conditions. Answer(s): D 3. Indicate which of the following events can occur during the processing of eukaryotic mRNA transcripts. Attachment of a poly (A) tail to the 5’ end of the transcript. Methylation of all G residues. Excisions of introns. Conversion of standard bases to modified bases such as inosine. Splicing together of exons. Differential cutting and splicing to produce two different proteins. Answer(s): CE 4. Although DNA replication has very high fidelity, mutations do occur. Which of the following types of single base-pair mutations would be most likely to be a lethal mutation? substitution insertion deletion silent B and C Answer(s): E 5. Which of the following correctly describes the nitrogen cycle? Fixation of atmospheric nitrogen by nitrogen-fixing bacteria yields bioavailable nitrate. Nitrate is reduced to ammonia in a process known as denitrification. Biological nitrogen fixation is carried out by a complex of proteins call the nitrogenase complex. A and B A, B, and C Answer(s): C 6. Assuming the 5’ 3’ connection of writing nucleotide sequence, indicate which of the following mRNA codons can be recognized by the tRNA anticodon ICG. UGC CGA UGA CGU CGC Answer(s): BDE 7. Both general recombination and transposon-type recombination: occur between homologous regions on chromosomes. are important in the repair of damaged DNA. involve RecA protein. generate genetic diversity. The two types of recombination have nothing in common. Answer(s):