國立屏東教育大學 97 學年度研究所碩士班入學考試
生物化學 試題
（應用化學暨生命科學系碩士班）
※請注意：1.本試題共四頁。
2.答案須寫在答案卷，否則不予計分。
Ⅰ. Multiple choice(please choose the best answer, 2 points each, 30%)
1. One method used to prevent disulfide bond interference with protein sequencing procedures
is:
A. cleaving proteins with proteases that specifically recognize disulfide bonds.
B. protecting the disulfide bridge against spontaneous reduction to cysteinyl sulfhydryl
groups.
C. reducing disulfide bridges and preventing their re-formation by further modifying
the —SH groups.
D. removing cystines from protein sequences by proteolytic cleavage.
E. sequencing proteins that do not contain cysteinyl residues.
2. In a mixture of the five proteins listed below, which should elute second in size-exclusion
(gel- filtration) chromatography?
A. cytochrome c
Mr = 13,000
B. immunoglobulin G
Mr = 145,000
C. ribonuclease A
Mr = 13,700
D. RNA polymerase
Mr = 450,000
E. serum albumin
Mr = 68,500
3. An  helix would be destabilized most by:
A. an electric dipole spanning several peptide bonds throughout the  helix.
B. interactions between neighboring Asp and Arg residues.
C. interactions between two adjacent hydrophobic Val residues.
D. the presence of an Arg residue near the carboxyl terminus of the  helix.
E. the presence of two Lys residues near the amino terminus of the  helix.
4. 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 rarely occurs in enzymes.
D. It results in a nonlinear Hill Plot.
E. It results in a sigmoidal binding curve.
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5. Compare the two reaction coordinate diagrams below and select the answer that correctly
describes their relationship. In each case, the single intermediate is the ES complex.
A. (a) describes a strict “lock and key” model, whereas (b) describes a transition-state
complementarity model.
B. The activation energy for the catalyzed reaction is #5 in (a) and is #7 in (b).
C. The activation energy for the uncatalyzed reaction is given by #5 + #6 in (a) and by #7 +
#4 in (b).
D. The contribution of binding energy is given by #5 in (a) and by #7 in (b).
E. The ES complex is given by #2 in (a) and #3 in (b).
6. An enzyme-catalyzed reaction was carried out with the substrate concentration initially a
thousand times greater than the Km for that substrate. After 9 minutes, 1% of the substrate
had been converted to product, and the amount of product formed in the reaction mixture was
12 mol. If, in a separate experiment, one-third as much enzyme and twice as much
substrate had been combined, how long would it take for the same amount (12 mol) of
product to be formed?
A. 1.5 min
B. 13.5 min
C. 27 min
D. 3 min
E. 6 min
7. When double-stranded DNA is heated at neutral pH, which change does not occur?
A. The absorption of ultraviolet (260 nm) light increases.
B. The covalent N-glycosidic bond between the base and the pentose breaks.
C. The helical structure unwinds.
D. The hydrogen bonds between A and T break.
E. The viscosity of the solution decreases.
8. Which of the following does not apply to the construction or use of a DNA library?
A. Determining the location of a particular DNA sequence in a DNA library requires a
suitable hybridization probe.
B. Genomic libraries are better for expressing gene products than cDNA libraries.
C. Many segments of DNA from a cellular genome are cloned.
D. Specialized DNA libraries can be made by cloning DNA copies of mRNAs.
E. The DNA copies of mRNA found in a cDNA library are made by reverse transcriptase.
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9. The technique known as yeast two hybrid analysis for detecting interacting gene products
depend on:
A. activation of DNA polymerase by the nearby binding of hybridizing protein complexes.
B. direct binding of a Gal4p activation domain to a DNA sequence in the promoter region.
C. having a promoter that responds directly to one of the two proteins whose interactions is
being measured.
D. hybridization of DNA segments corresponding to the two genes being examined.
E. stimulation of trasncription by interaction of two Gal4p domains via fused protein
sequences.
10.Which of these statements is generally true of integral membrane proteins?
A. A hydropathy plot reveals one or more regions with a high hydropathy index.
B. The domains that protrude on the cytoplasmic face of the plasma membrane nearly always
have covalently attached oligosaccharides.
C. They are unusually susceptible to degradation by trypsin.
D. They can be removed from the membrane with high salt or mild denaturing agents.
E. They undergo constant rotational motion that moves a given domain from the outer face of
a membrane to the inner face and then back to the outer.
11.Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine
because:
A. acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not.
B. acyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will
not.
C. carnitine is required to oxidize NAD+ to NADH.
D. fatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form.
E. None of the above is true.
12.Upon the addition of 2,4-dinitrophenol (DNP) to a suspension of mitochondria carrying out
oxidative phosphorylation linked to the oxidation of malate, all of the following occur except:
A. oxygen consumption decreases.
B. oxygen consumption increases.
C. the P/O ratio drops from a value of approximately 2.5 to 0.
D. the proton gradient dissipates.
E. the rate of transport of electrons from NADH to O2 becomes maximal.
13.Which of the following conversions require more than one step?
1. Alanine  pyruvate
2. Aspartate  oxaloacetate
3. Glutamate ketoglutarate
4. Phenylalanine  hydroxyphenylpyruvate
5. Proline  glutamate
A. 1 and 4
B. 1, 2, and 4
C. 1, 3, and 5
D. 2, 4, and 5
E. 4 and 5
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14.An elevated insulin level in the blood:
A. inhibits glucose uptake by the liver.
B. inhibits glycogen synthesis in the liver and muscle.
C. results from a below-normal blood glucose level.
D. stimulates glycogen breakdown in liver.
E. stimulates synthesis of fatty acids and triacylglycerols in the liver.
15.Which of the following statements about metabolism in the mammalian liver is false?
A. Most plasma lipoproteins are synthesized in the liver.
B. The enzymatic complement of liver tissue changes in response to changes in the diet.
C. The liver synthesizes most of the urea produced in the body.
D. The presence of glucose 6-phosphatase makes liver uniquely able to release glucose into
the bloodstream.
E. When ingest excess fatty acids, liver will produce ketone bodies as fuel for brain and red
blood cell.
Ⅱ. Short essay (70%)
1. Each of the following reagents or conditions will denature a protein. For each, describe
briefly what the reagent/condition does to destroy native protein structure.(6%)
(a) detergent
(b) low pH
2. Explain why most multicellular organisms use an iron-containing protein for oxygen binding
rather than free Fe2+. Your answer should include an explanation of (a) the role of heme and
(b) the role of the protein itself. (8%)
3. A plasmid that encodes resistance to ampicillin and tetracycline is digested with the restriction
enzyme PstI, which cuts the plasmid at a single site in the ampicillin-resistance gene. The
DNA is then annealed with a PstI digest of human DNA, ligated, and used to transform E. coli
cells. (a) What antibiotic would you put in an agar plate to ensure that the cells of a bacterial
colony contain the plasmid? (b) What antibiotic-resistance phenotypes will be found on the
plate? (c) Which phenotype will indicate the presence of plasmids that contain human DNA
fragments? (6%)
4. Describe the relationship between a proto-oncogene and an oncogene, and explain how one
arises from the other. Explain how a mutation in a GTP-binding protein, can lead to
unregulated cell division. (10%)
5. A nonsense mutation was occurred in an important gene and produced a temperature sensitive
(ts) phenotype; the cell cannot grow if the temperature exceeds 42℃. A suppressor screen is
engaged to identify the cells which can reverse the phenotype. Describe two possible
mechanisms which arise from a second site mutation will suppress the ts phenotype. (10%)
6. Describe the composition, chemical properties, structure, and functions of biological
membrane. (10%)
7. Compare E. coli DNA polymerase I and II with regard to the biological function. (10%)
8. Please describe the biochemical mechanism of RNA splicing in cell. (10%)
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