Question 1

Matrix-Assisted Laser Desorption Ionization is a type of _______ technique.

Accepted Answer

A)  electrophoresis 
B)  ion exchange chromatography 
C)  affinity chromatography 
D)  mass spectrometry 
A)  electrophoresis 
B)  ion exchange chromatography 
C)  affinity chromatography 
D)  mass spectrometry D

Question 2

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 A

Question 3

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 E

Question 4

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 5

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 6

In any form of chromatography,how will a compound which interacts more strongly with the stationary phase elute compared to one that interacts less strongly?

Accepted Answer

A)  A compound interacting more strongly will elute earlier than one with weaker interactions. 
B)  A compound interacting more strongly will elute later than one with weaker interactions. 
C)  The order of elution has nothing to do with interactions with the stationary phase, but with interactions with the mobile phase. 
A)  A compound interacting more strongly will elute earlier than one with weaker interactions. 
B)  A compound interacting more strongly will elute later than one with weaker interactions. 
C)  The order of elution has nothing to do with interactions with the stationary phase, but with interactions with the mobile phase.

Question 7

Exhibit 5A The following diagram shows the anode,cathode,and pH gradient of an isoelectric focusing bed:
  Refer to Exhibit 5A.A mixture of asp,asn,and arg is placed in the bed where the pH is 7,and the current is turned on.From left to right,which best represents the final positions of the individual amino acids?

Accepted Answer

A)  asp asn arg 
B)  arg asn asp 
C)  asn asp arg 
D)  arg asp asn 
A)  asp asn arg 
B)  arg asn asp 
C)  asn asp arg 
D)  arg asp asn

Question 8

Which type of column is most affected by the shape of the protein,for example,comparing spherical and cigar-shaped proteins?

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 9

In a sample consisting of lysine,leucine,and glutamic acid,which will be eluted last from an anion exchange resin at pH 7?

Accepted Answer

A)  all three will be eluted at the same time 
B)  lysine 
C)  leucine 
D)  glutamic acid 
A)  all three will be eluted at the same time 
B)  lysine 
C)  leucine 
D)  glutamic acid

Question 10

Elution of proteins by means of a pH gradient would work best with this type of column:

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

Exhibit 5A The following diagram shows the anode,cathode,and 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 7,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

Question 12

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 alwayse 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 alwayse specific for one type of protein to be bound 
E)  there can be molecule specific ligands or group specific ligands

Question 13

What tends to happen to the percent recovery during a protein's purification?

Accepted Answer

A)  The number usually steadily increases during the purification. 
B)  The number usually steadily decreases during the purification. 
C)  The number usually stays fairly constant during the purification. 
D)  There is no general trend for percent recovery during a protein purification. 
A)  The number usually steadily increases during the purification. 
B)  The number usually steadily decreases during the purification. 
C)  The number usually stays fairly constant during the purification. 
D)  There is no general trend for percent recovery during a protein purification.

Question 14

The degree of separation in molecular sieve chromatography depends on

Accepted Answer

A)  the polarity of the mobile phase 
B)  the pKa of the buffer material in the mobile phase 
C)  the chemical nature of the sieve material 
D)  the size of the pores in the sieve material 
A)  the polarity of the mobile phase 
B)  the pKa of the buffer material in the mobile phase 
C)  the chemical nature of the sieve material 
D)  the size of the pores in the sieve material

Question 15

Generally speaking,sequence techniques have become so sensitive that if you are able to isolate the protein on a gel,there is enough of it to get a significant amount of its sequence.

Accepted Answer

A) True 
 B)False

Question 16

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 17

Which would be best to separate positively charged proteins?

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 18

It is impossible to sequence a protein if you do not have overlapping sequences to work with.

Accepted Answer

A) True 
 B)False

Question 19

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 20

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.

Exam 5: Protein Purification and Characterization Techniques

Matrix-Assisted Laser Desorption Ionization is a type of _______ technique.

Using differential centrifugation it is possible to separate

Which separates based on the ionic charge on a protein?

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

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 any form of chromatography,how will a compound which interacts more strongly with the stationary phase elute compared to one that interacts less strongly?

Which type of column is most affected by the shape of the protein,for example,comparing spherical and cigar-shaped proteins?

In a sample consisting of lysine,leucine,and glutamic acid,which will be eluted last from an anion exchange resin at pH 7?

Elution of proteins by means of a pH gradient would work best with this type of column:

Exhibit 5A The following diagram shows the anode,cathode,and 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 7,and the current were turned on,it would migrate closest to which of the following positions?

In affinity chromatography

What tends to happen to the percent recovery during a protein's purification?

The degree of separation in molecular sieve chromatography depends on

Generally speaking,sequence techniques have become so sensitive that if you are able to isolate the protein on a gel,there is enough of it to get a significant amount of its sequence.

Ammonium sulfate is useful in protein purification because

Which would be best to separate positively charged proteins?

It is impossible to sequence a protein if you do not have overlapping sequences to work with.

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

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

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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