Question 1

In gel filtration chromatography

Accepted Answer

A)  materials are separated based on their size, the smaller ones eluting first. 
B)  materials are separated based on their size, the larger ones eluting first. 
C)  materials are separated based on their hydrophobic nature, the more hydrophobic ones eluting first. 
D)  materials are separated based on their hydrophobic nature, the less hydrophobic ones eluting first. 
A)  materials are separated based on their size, the smaller ones eluting first. 
B)  materials are separated based on their size, the larger ones eluting first. 
C)  materials are separated based on their hydrophobic nature, the more hydrophobic ones eluting first. 
D)  materials are separated based on their hydrophobic nature, the less hydrophobic ones eluting first.

Question 2

Two-dimensional electrophoresis usually exploits these 2 different properties of proteins:

Accepted Answer

A)  Molecular weight and shape 
B)  Molecular weight and net charge 
C)  Molecular weight and isoionic pH 
D)  Isoionic pH and shape 
E)  Isoionic pH and net charge 
A)  Molecular weight and shape 
B)  Molecular weight and net charge 
C)  Molecular weight and isoionic pH 
D)  Isoionic pH and shape 
E)  Isoionic pH and net charge

Question 3

The typical order of differential centrifugation for organelles is (from slowest speed/lowest g to fastest speed/highest g):

Accepted Answer

A)  nuclei, microsomes, mitochondria & chloroplasts, cytosol, whole cells 
B)  whole cells, nuclei, mitochondria & chloroplasts, microsomes, cytosol 
C)  cytosol, microsomes, nuclei, mitochondria & chloroplasts, whole cells 
D)  nuclei, mitochondria & chloroplasts, whole cells, cytosol, microsomes 
E)  whole cells, cytosol, microsomes, nuclei, mitochondria & chloroplasts 
A)  nuclei, microsomes, mitochondria & chloroplasts, cytosol, whole cells 
B)  whole cells, nuclei, mitochondria & chloroplasts, microsomes, cytosol 
C)  cytosol, microsomes, nuclei, mitochondria & chloroplasts, whole cells 
D)  nuclei, mitochondria & chloroplasts, whole cells, cytosol, microsomes 
E)  whole cells, cytosol, microsomes, nuclei, mitochondria & chloroplasts

Question 4

Differential centrifugation at low speeds (several thousand RPM) is a useful step when

Accepted Answer

A)  organelles have been lysed. 
B)  enzymes of interest have different sizes. 
C)  cell membranes must be left intact. 
D)  ribosomes need to be broken down. 
E)  there are either organelles or debris to separate. 
A)  organelles have been lysed. 
B)  enzymes of interest have different sizes. 
C)  cell membranes must be left intact. 
D)  ribosomes need to be broken down. 
E)  there are either organelles or debris to separate.

Question 5

How many bands would be produced when hemoglobin is subjected to SDS-PAGE?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  2, but only if the size of the pores in the gel would allow two proteins of slightly different size to be separated 
A)  1 
B)  2 
C)  3 
D)  4 
E)  2, but only if the size of the pores in the gel would allow two proteins of slightly different size to be separated

Question 6

Determination of the sequence of amino acids in a peptide is done by

Accepted Answer

A)  x-ray crystallography 
B)  Edman degradation 
C)  treatment with cyanogen bromide 
D)  trypsin hydrolysis 
A)  x-ray crystallography 
B)  Edman degradation 
C)  treatment with cyanogen bromide 
D)  trypsin hydrolysis

Question 7

The following methods are useful for cell homogenization:

Accepted Answer

A)  Sonication. 
B)  Freezing and thawing. 
C)  Detergents. 
D)  Enzymes. 
E)  All of these are correct. 
A)  Sonication. 
B)  Freezing and thawing. 
C)  Detergents. 
D)  Enzymes. 
E)  All of these are correct.

Question 8

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 9

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 10

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 11

The following are all principles on which to base electrophoresis except:

Accepted Answer

A)  Molecular size 
B)  Isoionic pH or pI 
C)  Net charge 
D)  Binding to a substrate 
E)  Shape 
A)  Molecular size 
B)  Isoionic pH or pI 
C)  Net charge 
D)  Binding to a substrate 
E)  Shape

Question 12

If a protein with the sequence PQRKYPIG is treated with trypsin,what will the products be?

Accepted Answer

A)  PQR KYPIG 
B)  PQRK YPIG 
C)  PQR K YPIG 
D)  PQ R KPIG0 
A)  PQR KYPIG 
B)  PQRK YPIG 
C)  PQR K YPIG 
D)  PQ R KPIG0

Question 13

Cyanogen bromide (CNBr) cleaves proteins

Accepted Answer

A)  after positively charged residues, such as K & R. 
B)  after negatively charged residues, such as D & E 
C)  after aromatic residues, such as Y & W. 
D)  after methionine residues. 
A)  after positively charged residues, such as K & R. 
B)  after negatively charged residues, such as D & E 
C)  after aromatic residues, such as Y & W. 
D)  after methionine residues.

Question 14

In affinity chromatography,a protein

Accepted Answer

A)  which binds to the ligand will remain on the column. 
B)  which binds to the ligand will elute from the column. 
C)  which is hydrophobic will remain on the column. 
D)  which is hydrophilic will remain on the column. 
A)  which binds to the ligand will remain on the column. 
B)  which binds to the ligand will elute from the column. 
C)  which is hydrophobic will remain on the column. 
D)  which is hydrophilic will remain on the column.

Question 15

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 16

When end-group analysis was done on the protein insulin,the results indicated that both glycine and phenylalanine were N-terminal amino acids and both asparagine and alanine were C-terminal amino acids.These results indicate that

Accepted Answer

A)  the experiment was done incorrectly 
B)  no conclusions can be drawn 
C)  there were impurities in the sample 
D)  insulin consists of two polypeptide chains 
A)  the experiment was done incorrectly 
B)  no conclusions can be drawn 
C)  there were impurities in the sample 
D)  insulin consists of two polypeptide chains

Question 17

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 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

Question 18

In electrophoresis experiments

Accepted Answer

A)  the separation must be carried out in bright light 
B)  the polarity of substances to be separated is more important than their charge or size 
C)  the sample can be badly degraded as a result of the separation 
D)  an electric field must be applied to the mixture to be separated 
A)  the separation must be carried out in bright light 
B)  the polarity of substances to be separated is more important than their charge or size 
C)  the sample can be badly degraded as a result of the separation 
D)  an electric field must be applied to the mixture to be separated

Exam 5: Protein Purification and Characterization Techniques

In gel filtration chromatography

Two-dimensional electrophoresis usually exploits these 2 different properties of proteins:

The typical order of differential centrifugation for organelles is (from slowest speed/lowest g to fastest speed/highest g):

Differential centrifugation at low speeds (several thousand RPM) is a useful step when

How many bands would be produced when hemoglobin is subjected to SDS-PAGE?

Determination of the sequence of amino acids in a peptide is done by

The following methods are useful for cell homogenization:

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

In isoelectric focusing gel electrophoresis

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

The following are all principles on which to base electrophoresis except:

If a protein with the sequence PQRKYPIG is treated with trypsin,what will the products be?

Cyanogen bromide (CNBr) cleaves proteins

In affinity chromatography,a protein

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

When end-group analysis was done on the protein insulin,the results indicated that both glycine and phenylalanine were N-terminal amino acids and both asparagine and alanine were C-terminal amino acids.These results indicate that

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 11,and the current were turned on,it would migrate closest to which of the following positions?

In electrophoresis experiments

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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