Chapter 5: Proteins: Primary Structure

Transcription

1 Instant download and all chapters Test Bank Fundamentals of Biochemistry Life at the Molecular Level 4th Edition Donald Voet 4th-edition-donald-voet/ Chapter 5: Proteins: Primary Structure Matching A) electrophoresis B) hydrophobic interaction C) enzyme-linked immunosorbent assay D) three-dimensional shape E) N-terminal amino acid F) negative charge G) nucleases H) chromophore I) foaming J) high level expression K) 2-mercaptoethanol L) positive charge M) cation exchange N) pi O) chymotrypsin P) C-terminal amino acid Q Sodium dodecyl sulfate 1. One of the reasons the primary structure is important for a protein is that it determines the the molecule adopts in aqueous solutions. Ans: D 2. If the cdna for a protein has been cloned, it may be possible to obtain large quantities of the protein by in bacteria. Ans: J

2 3. To help prevent denaturation of proteins in solution, steps are taken to avoid and adsorption to surfaces. Ans: I 4. Molecules that contain a(n) are capable of absorbing light. Ans: H 5. If antibodies to the protein being assayed are available, a(n) can be carried out. Ans: C 6. In general, proteins are least soluble in water when the ph is close to the. Ans: N Section: 5.2.B 7. chromatography is a method of fractionating a protein mixture according to differences in polarity. Section: 5.2.C

3 8. In order for DEAE to act as an anion exchanger, it must have a. Ans: L Section: 5.2.C 9. In chromatography, a protein mixture must be applied to the column at a low ph so that the proteins will have a net positive charge and bind to the column. Ans: M Section: 5.2.C 10. In SDS-PAGE, disulfide-linked polypeptides can be separated after reacting the protein first with. Ans: K Section: 5.2.D 11. Either dansyl chloride or Edman's reagent can be used to identify the of a protein. Section: 5.3.A Learning objective: Protein Sequencing 12. The endoprotease cleaves polypeptides on the C-terminal side of certain bulky hydrophobic amino acid residues. Ans: O Section: 5.3.B Learning objective: Protein Sequencing

4 Multiple Choice 13. Proteins are synthesized in vivo by the translation of A) cdna. B) trna. C) rrna. D) exons. E) mrna. 14. Since there are 20 standard amino acids, the number of possible linear polypeptides of length N can be expressed as: A) n 20 B) 20 n C) n D) n 20 E) n Natural proteins most commonly contain linear polypeptides between 100 and 1000 residues in length. One of the reasons polypeptides outside this range may be disfavored is that A) larger polypeptides would likely be insoluble. B) smaller polypeptides do not form stable folded structures. C) smaller polypeptides typically assemble into prion-like aggregates. D) amide linkages are not strong enough to keep larger polypeptides intact. E) ribosomes are unable to synthesize larger polypeptides.

5 16. The vast majority of polypeptides contain between amino acid residues. A) 10 and 50 B) 50 and 100 C) 100 and 1000 D) 1000 and 2000 E) 2000 and 34,000 Ans: C 17. Which of the following has the most dramatic influence on the characteristics of an individual protein? A) the amino-acid sequence B) the amino-acid composition C) the location of its encoding gene within the genome D) the stereochemistry at the -carbon E) the sequence of trna molecules involved in its translation Ans: A 18. Which statement about insulin is correct? A) Insulin is composed of two polypeptides, the A chain and the B chain. B) Insulin contains an intrachain disulfide bond. C) Insulin contains interchain disulfide bonds. D) The A chain and the B chain of insulin are encoded by a single gene. E) All of the above are correct.

6 19. A fast and common method for determining the protein concentration in column effluent is A) tandem mass spectrometry. B) salting in with ammonium sulfate. C) drying a portion and weighing the solid. D) measuring light absorption at 280 nm. E) Edman degradation. Ans: D 20. The salting in of proteins can be explained by: A) salt counter-ions reducing electrostatic attractions between protein molecules. B) salt ions reducing the polarity of the solution. C) salt ions increasing the hydrophobic interactions. D) releasing hydrophobic proteins from nonpolar tissue environments. E) hydration of the salt ions reducing solubility of proteins. Ans: A 21. The quantitation of proteins due to their absorbance at ~280 nm (UV region) is due to the large absorbtivity of the amino acids. A) anionic B) dansylated C) cleaved D) polar E) aromatic

7 22. Which of the following assays would be most specific for a particular protein? A) Bradford assay B) UV absorptivity C) radioimmunoassay D) molar absorptivity E) amino acid analysis Ans: C 23. An enzyme-linked immunosorbent assay requires A) a radioactive substrate. B) a radioactive standard for binding to the antibody. C) aromatic amino acids. D) an antibody that binds the protein of interest. E) a catalytic antibody. Ans: D 24. ELISA is an example of a(n): A) enzyme assay. B) biological assay. C) binding assay. D) immunological assay. E) none of the above Ans: D

8 25. You are purifying a nuclease by affinity chromatography. To determine which fractions contain the protein of interest, you test samples of all fractions for their ability to break down DNA. This is an example of A) a binding assay. B) a biological assay. C) an enzyme assay. D) an immunological assay. E) none of the above Ans: C 26. A radioimmunoassay requires A) an enzyme-linked antibody. B) a coupled enzymatic reaction. C) a radiolabeled antibody. D) a catalytic antibody. E) a radiolabeled standard protein that is used to compete for binding to the antibody. 27. Five graduate students prepare extracts from 5 different tissues. Each student measures the total amount of alcohol dehydrogenase and the total amount of protein in his or her extract. Which extract has the highest specific activity? Total protein (mg) Total alcohol dehydrogenase activity (units) A ,000 B ,000 C ,000 D ,000 E ,000

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10 28. Which physical characteristic is not commonly used in protein separation? A) solubility B) stereochemistry C) size D) charge E) polarity Section: 5.2.B 29. Adding additional salt to a protein solution can cause: A) an increase in solubility called salting in. B) a decrease in solubility called salting out. C) protein precipitation from solution. D) all of the above E) none of the above Ans: D Section: 5.2.B 30. A first step in purifying a protein that was initially associated with fatty substances would be A) Coomassie Brilliant Blue dye staining. B) analytical ultracentrifugation. C) ELISA. D) Western blotting. E) hydrophobic interaction chromatography. Section: 5.2.C

11 31. The acronym HPLC stands for A) hydrophobic protein liquid chromatography. B) high performance liquid chromatography. C) hydrophilic partition liquid chromatography. D) high priced liquid chromatography. E) hydrostatic process liquid chromatography. Section: 5.2.C