Test
Theme 2.2
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Preguntas del test (50)
1Proteins are synthesized in vivo by the translation of
- AcDNA
- BtRNA
- CrRNA
- Dexons
- EmRNA
2Since there are 20 standard amino acids, the number of possible linear polypeptides of length N can be expressed as:
- An x 20
- B20^n
- C20 × 10^n
- D10^20
- En x 10^20
3Natural proteins most commonly contain linear polypeptides between 100 and 1000 residues in length. One of the reasons
- Alarger polypeptides would likely be insoluble.
- Bsmaller polypeptides do not form stable folded structures.
- Csmaller polypeptides typically assemble into prion-like aggregates.
- Damide linkages are not strong enough to keep larger polypeptides intact.
- Eribosomes are unable to synthesize larger polypeptides.
4The vast majority of polypeptides contain between ______ amino acid residues.
- A10 and 50
- B50 and 100
- C100 and 1000
- D1000 and 2000
- E2000 and 34,000
5Which of the following has the most dramatic influence on the characteristics of an individual protein?
- Athe amino-acid sequence
- Bthe amino-acid composition
- Cthe location of its encoding gene within the genome
- Dthe stereochemistry at the alpha-carbon
- Ethe sequence of tRNA molecules involved in its translation
6Which statement about insulin is correct?
- AInsulin is composed of two polypeptides, the A chain and the B chain.
- BInsulin contains an intrachain disulfide bond.
- CInsulin contains interchain disulfide bonds.
- DThe A chain and the B chain of insulin are encoded by a single gene.
- EAll of the above are correct.
7The salting in of proteins can be explained by:
- Asalt counter-ions reducing electrostatic attractions between protein molecules.
- Bsalt ions reducing the polarity of the solution.
- Csalt ions increasing the hydrophobic interactions.
- Dreleasing hydrophobic proteins from nonpolar tissue environments.
- Ehydration of the salt ions reducing solubility of proteins.
8The quantitation of proteins due to their absorbance at ~280 nm (UV region) is due to the large absorbtivity of the ________ amino acids
- Aanionic
- Bdansylated
- Ccleaved
- Dpolar
- Earomatic
9Which of the following ‘assays’ would be most specific for a particular protein?
- ABradford assay
- BUV absorptivity
- Cradioimmunoassay
- Dmolar absorptivity
- Eamino acid analysis
10An enzyme-linked immunosorbent assay requires
- Aa radioactive substrate.
- Ba radioactive standard for binding to the antibody.
- Caromatic amino acids.
- Dan antibody that binds the protein of interest.
- Ea catalytic antibody.
11ELISA is an example of a(n):
- Aenzyme assay.
- Bbiological assay.
- Cbinding assay.
- Dimmunological assay.
- Enone of the above
12You 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
- Aa binding assay.
- Ba biological assay.
- Can enzyme assay.
- Dan immunological assay.
13A radioimmunoassay requires
- Aan enzyme-linked antibody.
- Ba coupled enzymatic reaction.
- Ca radiolabeled antibody.
- Da catalytic antibody.
- Ea radiolabeled standard protein that is used to compete for binding to the antibody.
14Five 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 300 60,000
B 200 80,000
C 3000 96,000
D 5000 100,000
E 1000 200,000- Aa
- Bb
- Cc
- Dd
- Ee
15Which physical characteristic is not commonly used in protein separation?
- Asolubility
- Bstereochemistry
- Csize
- Dcharge
- Epolarity
16Adding additional salt to a protein solution can cause:
- Aan increase in solubility called ‘salting in’.
- Ba decrease in solubility called ‘salting out’.
- Cprotein precipitation from solution.
- Dall of the above
- Enone of the above
17A first step in purifying a protein that was initially associated with fatty substances would be
- ACoomassie Brilliant Blue dye staining.
- Banalytical ultracentrifugation.
- CELISA.
- DWestern blotting.
- Ehydrophobic interaction chromatography.
18The acronym HPLC stands for
- Ahydrophobic protein liquid chromatography.
- Bhigh performance liquid chromatography.
- Chydrophilic partition liquid chromatography.
- Dhigh priced liquid chromatography
- Ehydrostatic process liquid chromatography.
19A technique that can be used to separate proteins based primarily on the presence of non-polar residues on their surface is called
- Aion-exchange chromatography
- Bgel filtration chromatography
- Caffinity chromatography
- Dgel electrophoresis
- Ehydrophobic interaction chromatography
20A technique that can be used to separate proteins based primarily on their pI is called
- Aion-exchange chromatography.
- Bgel filtration chromatography.
- Caffinity chromatography
- Disoelectric focusing.
- Ehydrophobic interaction chromatography.
21Which of the following amino acids would be last to elute at pH 8.0 from an anion-exchange column?
- Alysine
- Balanine
- Cglutamic acid
- Dasparagine
- Eglycine
22Which of the following amino acids would be first to elute at pH 8.0 from an anion-exchange column?
- Alysine
- Balanine
- Cglutamic acid
- Dasparagine
- Eglycine
23The pK1, pK2, and pKR of the amino acid lysine are 2.2, 9.1, and 10.5, respectively. The pK1, pK2, and pKR of the amino acid arginine are 1.8, 9.0, and 12.5, respectively. A student at SDSU wants to use ion exchange chromatography to separate lysine from arginine. What pH is likely to work best for this separation?
- A1.5
- B2.5
- C5.5
- D7.5
- E10.5
24The pK1, pK2, and pKR of the amino acid histdine are 1.8, 9.3, and 6.0, respectively. The pK1, pK2, and pKR of the amino acid arginine are 1.8, 9.0, and 12.5, respectively. You have a mixture of histidine and arginine, how would you try to separate these two amino acids?
- Aanion exchange chromatography at pH 2
- Banion exchange chromatography at pH 4
- Ccation exchange chromatography at pH 2
- Dcation exchange chromatography at pH 4
- Ecation exchange chromatography at pH 9
25What can be done to increase the rate at which a protein of interest moves down an ion-exchange chromatography column?
- Areduce the ion concentration in the eluant
- Badd a small amount of a non-ionic detergents to the eluant
- Cchange the pH of the eluant
- Dadd a protease inhibitor to the eluant
- Ereduce the temperature of the eluant
26Hydrophobic interaction chromatography can be used to separate proteins based on differences in
- Aionic charge
- Bsolubility
- Csize
- Dpolarity
- Ebinding specificity.
27You are trying to separate five proteins, which are listed below, by gel filtration chromatography. Which of the proteins will elute first from the column?
- Acytochrome c (12 kDa)
- BRNA polymerase (99 kDa)
- Cglutamine synthetase (621 kDa)
- Dinterferon-y (34 kDa)
- Ehemoglobin (62 kDa)
28SDS-PAGE separates proteins primarily due to differences in
- Aisoelectric point.
- Bmass.
- Cpolarity.
- Dsolubility.
- Eamino acid sequence.
29Which of these techniques is used to separate proteins mainly based on mass?
- Apolyacrylamide gel electrophoresis (in the absence of SDS)
- BSDS-PAGE
- Cisoelectric focusing
- Dimmunoblotting
- EWestern blotting
30Which of these techniques uses antibodies to detect very small amounts of specific proteins following separation by SDS-PAGE.
- Aimmunoblotting
- Bsilverstaining
- CCoomassie Brilliant Blue staining
- DELISA
- ERIA
31Disulfide bonds can be cleaved using
- Aiodoacetate.
- Bdansyl chloride.
- C2-mercaptoethanol (beta-ME).
- Dtrypsin
- Ephenylisothiocyanate.
32Which of these reagents is commonly used to determine the number of polypeptides in a protein?
- Aiodoacetate
- Bdansyl chloride
- C2-mercaptoethanol (beta-ME)
- Dcyanogen bromide
- EDEAE
33Enzymes that hydrolyze the internal peptide bonds (not the peptide bonds of the terminal amino acids) of a protein are classified
- Aoxidoreductases.
- Blyases.
- Cendopeptidases.
- Dnucleases.
- Eexopeptidases.
34Which of the following substances cannot be used to cleave peptide bonds in polypeptides?
- Atrypsin
- Bcyanogen bromide
- Cendopeptidases
- D2-mercaptoethanol
- Epepsin
35Which of these are commonly used to cleave peptide bonds in polypeptides?
- A2-mercaptoethanol
- Bdansyl chloride
- Ciodoacetate
- Dsodium dodecyl sulfate
- Etrypsin
36The peptide Leu─Cys─Arg─Ser─Gln─Met is subjected to Edman degradation. In the first cycle the peptide first reacts with phenylisothiocyanate under basic conditions. The product of this reaction is incubated with anhydrous trifluoroacetic acid and subsequently with an aqueous acid. What are the products generated in the first cycle.
- APTH─Leu, PTH─Cys, PTH─Arg, PTH─Ser, PTH─Gln, and PTH─Met
- BPTH─Leu─Cys─Arg─Ser─Gln─Met
- CPTH─Met and Leu─Cys─Arg─Ser─Gln─Met
- DPTH─Leu─Cys and PTH─Arg─Ser─Gln─Met
- EPTH─Leu and Cys─Arg─Ser─Gln─Met
37Edman degradation can be used to
- Aidentify the N-terminal amino acid of a polypeptide.
- Bidentify the C-terminal amino acid of a polypeptide.
- Cseparate the subunits of a multi-subunit protein.
- Dcleave a protein at specific sites.
- Ecleave disulfide bonds within a protein so that the individual polypeptides can be separated.
38Although a protein’s primary sequence can be inferred from the nucleotide sequence, modifications such as ______ can be determined most easily by tandem mass spectrometry followed by protein database searching.
- Aphosphorylation
- Bdisulfide crosslinks
- Cglycosylation
- Dacetylation
- Eall of the above
39The positive charge on proteins in electrospray ionization mass spectrometry is the result of
- Aprotons fired at the gas-phase protein molecules.
- Bprotonated side chains of Asp and Glu residues.
- Cprotonated side chains of Arg and Lys residues.
- Da high pH.
- Eelectrons fired at the gas-phase protein molecules.
40______________ has emerged as a technique for protein sequencing.
- ANMR spectroscopy
- BMass spectrometry
- CGel electrophoresis
- DPhylogenetic analysis
- ELimited proteolysis
41Protein sequences are customarily ‘reconstructed’ from sequenced fragments because
- Aprotein purification invariably results in the fragmentation of the protein of interest.
- Bproteins are naturally and inevitably cleaved by proteolytic enzymes.
- Cproteins are composed of multiple subunits.
- Dlarge polypeptides cannot be directly sequenced.
- Eall of the above
42You have purified a new peptide hormone. To determine its amino acid sequence you have digested the polypeptide with trypsin and in a separate reaction you have cleaved the polypeptide with cyanogen bromide.
Cleavage with trypsin yielded 5 peptides that were sequenced by Edman degradation as shown in the following.
1. Ser─Leu
2. Asp─Val─Arg
3. Val─Met─Glu─Lys
4. Ser─Gln─Met─His─Lys
5. Ile─Phe─Met─Leu─Cys─Arg
Cleavage with cyanogen bromide yielded 4 peptides that were sequenced by Edman degradation:
1. His─Lys─Ser─Leu
2. Asp─Val─Arg─Val─Met
3. Glu─Lys─Ile─Phe─Met
4. Leu─Cys─Arg─Ser─Gln─Met
Determine the identity of the N-terminal amino acid after reconstructing the intact protein.- Aasp
- Bser
- Chis
- Dglu
- Eile
43In two homologous proteins, which residue is most likely to replace a Glu residue as a conservative substitution?
- Aasp
- Btrp
- Cmet
- Dile
- Elys
44A phylogenetic tree depicts ___________ of proteins.
- Afolding patterns
- Bhypervariable residues
- Cinvariable residues
- Devolutionary relationships
- Egene sequences
45A protein that has had few changes in its amino acid sequence over evolutionary history is labeled
- Aa fibrinopeptide.
- Bevolutionarily conserved.
- Crandom.
- Da product of pseudogenes.
- Ephylogenetic.
46 Paralogous genes are
- Agenes that do not encode protein.
- Bgenes of slowly evolving proteins.
- Crelics of genes that are not expressed.
- Dgenes of rapidly evolving proteins.
- Ethe results of gene duplication.
47A fast way for nature to generate new proteins is:
- Ageneration of pseudogenes.
- Bmutation by neutral drift.
- Cshuffling protein domains or motifs.
- Dhypervariable positions.
- Eliberal substitution.
48___________ is an example of a very slowly evolving protein.
- AHistone H4
- BHemoglobin
- CCytochrome c
- DFibrinopeptides
- Enone of the above
49Proteins are often constructed from multiple segments of 40-200 amino acid residues, commonly called
- Apseudogenes.
- Bhypervariable residues.
- Cprotolytic fragments.
- Ddomains.
- Esubunits.
50In a conjugated protein, a prosthetic group is:
- Aa fibrous region of a globular protein.
- Ba nonidentical subunit of a protein with many identical subunits.
- Ca part of the protein that is not composed of amino acids.
- Da subunit of an oligomeric protein
- Esynonymous with “protomer.”
Información
- Descripción
- prot est. 1ria
- Autor
- Aly Lzo
- Idioma
- English
- Visitas
- 133
- Valoración
- Aún sin valoraciones Valora este test