Question 1

Which of the following are principles on which to base column chromatography?

Accepted Answer

A)   Molecular size
B)   Isoionic pH or pI
C)   Ion exchange
D)   Both molecular size and ion exchange
E)   All of theseF) A) and B)
G) A) and E)

Question 2

In isoelectric focusing gel electrophoresis

Accepted Answer

A)   particular care must be taken to ensure the same pH along the length of the gel
B)   there is a pH gradient that parallels the electric field gradient
C)   the electric current is allowed to fluctuate
D)   the electric circuits of the apparatus must be very well insulatedE) B) and D)
F) B) and C)

Question 3

In affinity chromatography

Accepted Answer

A)   there is nonspecific binding of proteins to column material
B)   only minor purifications can be obtained
C)   the mobile phase is always pure water
D)   the ligand is always specific for one type of protein to be bound
E)   there can be molecule specific ligands or group specific ligandsF) All of the above
G) B) and E)

Question 4

The typical order for the major steps of enzyme isolation would be (from first to last) :

Accepted Answer

A)   Homogenization, salt fractionation, electrophoresis, column chromatography.
B)   Homogenization, column chromatography, salt fractionation, electrophoresis.
C)   Homogenization, salt fractionation, column chromatography, electrophoresis.
D)   Salt fractionation, homogenization, electrophoresis, column chromatography.
E)   Homogenization, electrophoresis, salt fractionation, column chromatography.F) A) and E)
G) A) and B)

Question 5

The isoelectric point is

Accepted Answer

A)   the pH at which a substance has no net charge
B)   the pH at which a substance has a net positive charge
C)   the pH at which a substance has a net negative charge
D)   the pH at which a substance has no charge groups of any kindE) B) and C)
F) A) and C)

Question 6

When electrophoretic separations are done based on molecular weight, the distance that a molecule moves can be graphed as a straight line when compared to:

Accepted Answer

A)   the MW of the proteins
B)   the negative of the MW of the proteins
C)   the log of the MW of the proteins
D)   none of theseE) None of the above
F) C) and D)

Question 7

Which would be best to separate a protein that binds strongly to its substrate?

Accepted Answer

A)   Gel filtration
B)   Affinity chromatography
C)   Cation exchange
D)   Anion exchange
E)   Cation or anion exchangeF) C) and E)
G) C) and D)

Question 8

The most efficient method for determining the sequence of a short peptide is:

Accepted Answer

A)   Edman degradation
B)   Trypsin digestion
C)   Chymotrypsin digestion
D)   Cyanogen bromide digestionE) All of the above
F) A) and B)

Question 9

Ammonium sulfate is useful in protein purification because

Accepted Answer

A)   it contains nitrogen and sulfur, both of which occur in proteins
B)   it is sparingly soluble in water, causing proteins to co-precipitate with it
C)   very pure proteins are obtained when it is used
D)   it forms ion-dipole interactions with water, making proteins less soluble and more likely to precipitateE) None of the above
F) B) and D)

Question 10

Salting out with ammonium sulfate is based upon proteins interacting with other proteins via

Accepted Answer

A)   hydrogen bonds.
B)   ionic bonds.
C)   hydrophobic interactions.
D)   disulfide bonds.E) B) and D)
F) B) and C)

Question 11

Which separates on the basis of molecular weight?

Accepted Answer

A)   Gel filtration
B)   Affinity chromatography
C)   Cation exchange
D)   Anion exchange
E)   Cation or anion exchangeF) B) and E)
G) B) and D)

Question 12

Which separates based on the ionic charge on a protein?

Accepted Answer

A)   Gel filtration
B)   Affinity chromatography
C)   Cation exchange
D)   Anion exchange
E)   Cation or anion exchangeF) A) and D)
G) C) and E)

Question 13

Using differential centrifugation it is possible to separate

Accepted Answer

A)   nuclei, mitochondria, and ribosomes into three separate fractions
B)   organelles from contaminating salts
C)   proteins that differ in charge
D)   proteins from membranesE) B) and C)
F) None of the above

Question 14

In the SDS-PAGE (sodium dodecylsulfate - polyacrylamide gel electrophoresis)  method, separation takes place on the basis of

Accepted Answer

A)   charge only, because all particles have different charges, but the same mass.
B)   the sieving action of the gel, because all particles have the same charge, but different masses.
C)   the sieving action of the gel, because all particles have approximately the same charge/mass ratio, but different masses.
D)   the chemical nature of the buffer used as the electrolyte.E) None of the above
F) All of the above

Question 15

Exhibit 5A
The following diagram shows the anode, cathode, and  pH\mathrm { pH }pH  gradient of an isoelectric focusing bed:

-Refer to Exhibit 5A. If the amino acid glycine were placed in the bed where the pH is 11, and the current were turned on, it would migrate closest to which of the following positions?

Accepted Answer

A)   pH 4
B)   pH 6
C)   pH 8
D)   pH 10 E) B) and C)
F) None of the above

Question 16

Which of the following is not an example of column chromatography?

Accepted Answer

A)   ammonium sulfate fractionation
B)   ion-exchange separation
C)   HPLC
D)   affinity separationE) B) and C)
F) A) and D)

Question 17

Methods for breaking proteins into smaller peptides include all of the following except:

Accepted Answer

A)   Digestion with chymotrypsin
B)   Cyanogen Bromide treatment
C)   Digestion with Trypsin
D)   Edmann degradation
E)   All of the above create short peptides suitable for sequencingF) C) and E)
G) A) and C)

Question 18

The order of elution of AAs H, E, & K from a cation exchange column by a pH 6 buffer is

Accepted Answer

A)   H E K
B)   E H K
C)   K H E
D)   E K HE) A) and B)
F) B) and C)

Question 19

An amino acid analyzer is an instrument used to determine

Accepted Answer

A)   the sequence of amino acids in a polypeptide chain
B)   the identity of N-terminal and C-terminal amino acids in a protein
C)   the presence of modified amino acids in a protein
D)   the identities and relative amounts of amino acids in a proteinE) None of the above
F) A) and D)

Question 20

In all forms of chromatography one way of identifying eluted substances is by

Accepted Answer

A)   fluorescence spectroscopy
B)   comparison with standards
C)   radioactive labeling
D)   treating fractions with a reagent that will cause a color changeE) C) and D)
F) A) and B)

Exam 5: Protein Purification and Characterization Techniques

The most efficient method for determining the sequence of a short peptide is:

Correct Answer
verified

In the SDS-PAGE (sodium dodecylsulfate - polyacrylamide gel electrophoresis) method, separation takes place on the basis of

Correct Answer
verified

Which separates on the basis of molecular weight?

Correct Answer
verified

Which of the following are principles on which to base column chromatography?

Correct Answer
verified

In isoelectric focusing gel electrophoresis

Correct Answer
verified

Salting out with ammonium sulfate is based upon proteins interacting with other proteins via

Correct Answer
verified

Using differential centrifugation it is possible to separate

Correct Answer
verified

In affinity chromatography

Correct Answer
verified

When electrophoretic separations are done based on molecular weight, the distance that a molecule moves can be graphed as a straight line when compared to:

Correct Answer
verified

The typical order for the major steps of enzyme isolation would be (from first to last) :

Correct Answer
verified

An amino acid analyzer is an instrument used to determine

Correct Answer
verified

The order of elution of AAs H, E, & K from a cation exchange column by a pH 6 buffer is

Correct Answer
verified

Which separates based on the ionic charge on a protein?

Correct Answer
verified

In all forms of chromatography one way of identifying eluted substances is by

Correct Answer
verified

Which would be best to separate a protein that binds strongly to its substrate?

Correct Answer
verified

Correct Answer
verified

Which of the following is not an example of column chromatography?

Correct Answer
verified

Ammonium sulfate is useful in protein purification because

Correct Answer
verified

Methods for breaking proteins into smaller peptides include all of the following except:

Correct Answer
verified

The isoelectric point is

Correct Answer
verified

Exam 5: Protein Purification and Characterization Techniques

The most efficient method for determining the sequence of a short peptide is:

Correct AnswerverifiedShow Answer

In the SDS-PAGE (sodium dodecylsulfate - polyacrylamide gel electrophoresis) method, separation takes place on the basis of

Correct AnswerverifiedShow Answer

Which separates on the basis of molecular weight?

Correct AnswerverifiedShow Answer

Which of the following are principles on which to base column chromatography?

Correct AnswerverifiedShow Answer

In isoelectric focusing gel electrophoresis

Correct AnswerverifiedShow Answer

Salting out with ammonium sulfate is based upon proteins interacting with other proteins via

Correct AnswerverifiedShow Answer

Using differential centrifugation it is possible to separate

Correct AnswerverifiedShow Answer

In affinity chromatography

Correct AnswerverifiedShow Answer

When electrophoretic separations are done based on molecular weight, the distance that a molecule moves can be graphed as a straight line when compared to:

Correct AnswerverifiedShow Answer

The typical order for the major steps of enzyme isolation would be (from first to last) :

Correct AnswerverifiedShow Answer

An amino acid analyzer is an instrument used to determine

Correct AnswerverifiedShow Answer

The order of elution of AAs H, E, & K from a cation exchange column by a pH 6 buffer is

Correct AnswerverifiedShow Answer

Which separates based on the ionic charge on a protein?

Correct AnswerverifiedShow Answer

In all forms of chromatography one way of identifying eluted substances is by

Correct AnswerverifiedShow Answer

Which would be best to separate a protein that binds strongly to its substrate?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following is not an example of column chromatography?

Correct AnswerverifiedShow Answer

Ammonium sulfate is useful in protein purification because

Correct AnswerverifiedShow Answer

Methods for breaking proteins into smaller peptides include all of the following except:

Correct AnswerverifiedShow Answer

The isoelectric point is

Correct AnswerverifiedShow Answer

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