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Quiz 5
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Questions in this quiz (19)
1A protein has a molecular mass of 200 kDa as determined by gel filtration (=native molecular weight). When separated by SDS-PAGE (without a reducing agent present) only one polypeptide appeared with a mass corresponding to 100 kDa. When determined by SDS-PAGE in combination with a reducing agent (DTT) exactly two polypeptides appeared of sizes 50 and 60 KDa. What is the correct structure of a native protein?
- AThe native protein is made up of 40 kDA and one 60 KDA polypeptides.
- BThe native protein is made up of two 100 kDa polypeptides.
- CThe native protein is made up of two 40 kDa and two 60 kDa polypeptides.
- DThe native protein si made up of four polypeptides: two 100 kDa polypeptides and one 40 kDa and one 60 kDA polypeptide.
2At any pH below the pl of the amino acid glycine, it will have a...
- AA net positive charge
- BA zero net charge
- CA net negative charge
- DOne fully positive and one fully negative charge
- EIts both carboxyl - and amino groups half dissociated.
3Which method of protein chromatography can accomplish the greatest level of purification in a single step?
- ASDS PAGE
- Baffinity chromatography
- Chydrophobic chromatography
- Dgel-filtration
- Eion-exchange
4In a mixture of the five proteins listed below, which should elute first in size exclusion chromatography?
- Acytochrome c, Mr = 13,000
- BImmunoglobulin G, Mr = 145,000
- COvalbumin, mr = 43,000
- DRNA polymerase, mr = 450,000
- Eserum albumin, mr = 68,500
5Electrophoresis in the presence of SDS separates proteins almost exclusively on the basis of
- Amass
- Bcharge
- Cshape
- Dpolarity
- Esolubility
6Electrophoresis in the presence of SDS separates proteins almost exclusively on the basis of:
- Amass
- Bcharge
- Cshape
- Dpolarity
- Esolubility
7The functional differences, as well as differences in three-dimensional structures, between two different enzymes from e. coli result directly from their different:
- Aaffinities for ATP
- Bamino acid sequences
- Croles in DNA metabolism
- Droles in metabolism of e. coli
- Esecondary structures
8Which of the following interactions is NOT a basis for an affinity chromatography procedure?
- Ahormone-receptor
- Bantigen-antibody
- Cdan-transcription factor
- Dnegative charge-positive charge
9Free amino acids are different from their residues in proteins by-
- AThe size of the R group
- BHaving a lower molecular weight
- Cbeing larger by the size of a water molecule
- D110 daltons
10the formation of a peptide bond between two amino acids is an example of an _______ reaction
- Acleavage
- Bwater elimination
- Cenol formation
- Dhydration
- Eall of the above
11Molecules that differ in size can be separated from each other by which of the following methods
- AIon exchange chromatography
- Baffinity chromatography
- Cgel-filtration chromatography
- Dall of the above
12In SDS-PAGE, the protein sample is typically treated with a reducing agent. This treatment allows-
- Ato separate large polypeptides from small polypeptides
- Bto denature proteins
- Cto sparate a multisubunit protein to its individual polypeptides
- Dto accelearate formation of disulfide bridges in proteins
- Enone of the above
13The peptide aspartylglutamylglycyltyrosylserine:
- AWill be easily dissolved in an aqueous solution
- Bhas 5 peptide bonds
- Chas no free carboxyl group
- Dmostly hydrophobic
14In affinity chromatography, the bound proteins are typicallty eluted by a solution containing:
- Asalt
- Bligand
- Cacid
- DA and B
- EA, B, and C
15Which of the following is FALSE with the respect tot he amino acid composition of proteins?
- AProteins that are closely related by evolution tend to have similarities in their composition and sequence.
- BProteins that are related by evolution have similar functions.
- CAmino acid sequence vary between proteins that have different functions.
- DProteins with similar amino acid compositions may not have similar functions.
- EProtein that contain more than one domain usually have more than one function.
16Before the eluant from the column is collected in the fraction collector:
- AIt is mixed with a buffer to lower the ion concentration
- BIt passes through a spectrophotometer
- CIt is heated for a short period and sterilized
- DIt is first collected in a large cylinder and then dispensed into smaller vials.
- EAll of the above.
17The flow-through fraction in ion change chromatography of amino acids in which an anion exchange resin was used is expected to contain
- Anegatively charged amino acids
- Bpositively charged AAs
- Cpolar AAs
- Dnon-polar AAs
- Eall answers are correct
18Four proteins, each containing a single polypeptide, are separated by SDS-PAGE: human cytochrome c (MW 13,000), human serum albumin (MW 67,000), bovine myoglobin (MW 16,890), and human apolipoprotein B (MW 513,000). Which one would show up as the band at the bottom of the gel?
- Acytochrome C
- Bapolipoprotein B
- CBovine myoglobin
- Dserum albumin
- Ecan't tell from data provided
19Which of the following pentapeptides is expected to be the BEST dissolved in water?
- ANH2 - ser - pro- gly - ala- cys - asn - COOH
- BNH2 - tyr - thr - gly - ser - gln - asp - COOH Correct
- CNH2 - ser - ala - gly - phe - gln - asp - COOH
- DNH2 - gly - leu - phe - val - ser - gly - COOH
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- Quiz on Quiz 5, created by genny stubbs on 14/06/2017.
- Author
- genny stubbs
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- English
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- History
- Created on 14 Jun 2017 · updated on 14 Jun 2017
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