27. A teacher synthesized a peptide and asked his students to describe the amino acid residues in the peptide. Student A said: "This peptide contains the amino acid residue which might be phosphorylated". Student B said: "This peptide contains the amino acid residue which has 2 chiral centers". Student C said: "This peptide does not contain the amino acid residue which could be cleaved by CNBr'. Student D said: "This peptide does not contain the amino acid residue which could be modified with N-linked glycan in glycoproteins. Student E said: "The pI of this peptide is around

7". The sequence of this peptide should be:

(A) ASQHPIMLWG
(B) CVKILVGAEQNR
(C) AVEFFTRDQPHK
(D) AYKLWPIEAGQA
(E) RGDSSERTVVNCA

23. Protein translation begins: (A) at the replication fork.(B)on the(C)at the start codon.  (D) in nucleus. (E) All of these

24. Eukaryotic mRNA binding to the ribosomes is facilitated by_______. (A) the Shine Dalgarno sequence (B) the 7-methyl guanosine cap (C)tRNA(D) snRNA (E) All of the above

25. Cellulose fibers resemble with the protein structure in the form of: (A) β-sheets. (B) α-helices. (C) β-turns. (D)AII of the above(E) both β-sheets and u-helices. 

26. Which description is correct? (A) Organisms which could use light as energy source are classified as autotrophs. (B) Microtubules and intermediate filaments help to produce motion of organelles or of the whole cell. (C) Isoleucine has four stereoisomers. (D) H.O in liquid water forms more hydrogen bonds than in ice. (E) I M NaCl and 1 M H.SO, has the same osmolarity.

複選題28. Please choose the correct answer(s) from the following descriptions:  1. Fructose is not reducing sugar.  2. The α-D-glucose and β-D-glucose interconvert in aqueous solution. 3. GIc(β1→4)Glc could be draw as the following figure.  4. The sugar drawn above is a maltose. 5. Mannose is a C2 epimer of galactose. (A) Only land 2 are correct. (B) 1, 3, and 4 are correct. (C)1 and 5 are correct.(D) 2, 3, and 4 are correct. (E) Only 5 is incorrect.

29. A protein mixture contains proteins A, B, and C (Protein A: homodimer M. = 140,000, pI 8； Protein B: Mr = 113,000, pI 5； Protein C: Mr = 13,000, pI 9). 1. Sandy used SDS-PAGE to separate theses three proteins. The sequence of the protein bands shown in gel from top to bottom is A-B-C. 2. Simon dissolved the protein mixture in 20 mM phosphate buffer (pH 7) and loaded to a cation exchange column equilibrated with the same buffer. Protein B could not bind to the column.  3. Samuel dissolved the protein mixture in 20 mM phosphate bufter (pH 7) and loaded to an anion exchange column equilibrated with the same buffer. Only protein A and C could bind to the column. 4. Silvia used a gel filtration column to separate them, C will be eluted first.  5. Sophie used 2-Dimensional electrophoresis to separate them. The relative positions of these three proteins is like the image below.  (A) 1, 2, and 5 are correct. (B) 2 and 4 are incorrect. (C) 1, 3, and 4 are incorrect.(D) Only 2 is correct.  (E) Only land 3 are incorrect.

30. The following figure describes the torsion angle of the residue i in a protein. What does the figure tell you? (A) It is Φ angle -90 degrce. (B) It isωangle +90 degree. (C) It is Φ angle t90 degree. (D) It is φ angle -90 degree. (E) It is Φ angle +90 degree

31. Which of the following is not correct concerning cooperative binding of a ligand to a protein? (A) It is usually a form of allosteric interaction. (B) It is usually associated with proteins with multiple subunits. (C) It results in a sigmoidal binding curve. (D) It rarely occurs in enzymes. (E) It results in a nonlinear Hill Plot.

32. In the following diagram of the first step in the reaction catalyzed by the protease chymotrypsin, the process of general base catalysis is illustrated by the number__________ , and the process of covalent catalysis is illustrated by the number ____________.(A) 3；2 (B) 1；3 (C) 2；3 (D) 2； 1

33. The steady state assumption, as applied to enzyme kinetics, implies: (A) the ES complex is formed and broken down at equivalent rates. (B) the enzyme is regulated. (C) Km=Ks. (D) the Km is equivalent to the cellular substrate concentration. (E) the maximum velocity occurs when the enzyme is saturated.