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

Question 2

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 protein 
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 protein

Question 3

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

Question 4

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 ligands 
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 ligands

Question 5

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

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 these 
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 these

Question 7

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 insulated 
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 insulated

Question 8

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. 
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.

Question 9

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 digestion 
A)  Edman degradation 
B)  Trypsin digestion 
C)  Chymotrypsin digestion 
D)  Cyanogen bromide digestion

Question 10

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

Question 11

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

Question 12

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 H 
A)  H E K 
B)  E H K 
C)  K H E 
D)  E K H

Question 13

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

Question 14

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 kind 
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 kind

Question 15

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

Question 16

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 sequencing 
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 sequencing

Question 17

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. 
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.

Question 18

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 membranes 
A)  nuclei, mitochondria, and ribosomes into three separate fractions 
B)  organelles from contaminating salts 
C)  proteins that differ in charge 
D)  proteins from membranes

Question 19

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 precipitate 
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 precipitate

Question 20

Exhibit 5A
The following diagram shows the anode, cathode, and $\mathrm { pH }$ 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 
A)  pH 4 
B)  pH 6 
C)  pH 8 
D)  pH 10

Exam 5: Protein Purification and Characterization Techniques

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

An amino acid analyzer is an instrument used to determine

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

In affinity chromatography

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

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:

In isoelectric focusing gel electrophoresis

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

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

Which separates based on the ionic charge on a protein?

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

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

Which separates on the basis of molecular weight?

The isoelectric point is

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

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

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

Using differential centrifugation it is possible to separate

Ammonium sulfate is useful in protein purification because

Biochemistry and the Organization of Cells

Water: the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three-Dimensional Structure of Proteins

The Behavior of Proteins: Enzymes

The Behavior of Proteins: Enzymes, Mechanisms, and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids: How Structure Conveys Information

Biosynthesis of Nucleic Acids: Replication

Transcription of the Genetic Code: Biosynthesis of RNA

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism: Cellular Signaling

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