Question 1

Proteins are often constructed from multiple segments of 40-200 amino acid residues,commonly called

Accepted Answer

A) pseudogenes. 
B) hypervariable residues. 
C) protolytic fragments. 
D) domains. 
E) subunits. 
A) pseudogenes. 
B) hypervariable residues. 
C) protolytic fragments. 
D) domains. 
E) subunits.

Question 2

A fast and common method for determining the protein concentration in column effluent is

Accepted Answer

A) tandem mass spectrometry. 
B) salting in with ammonium sulfate. 
C) drying a portion and weighing the solid. 
D) measuring light absorption at 280 nm. 
E) Edman degradation. 
A) tandem mass spectrometry. 
B) salting in with ammonium sulfate. 
C) drying a portion and weighing the solid. 
D) measuring light absorption at 280 nm. 
E) Edman degradation.

Question 3

You are purifying a nuclease by affinity chromatography.To determine which fractions contain the protein of interest,you test samples of all fractions for their ability to break down DNA.This is an example of

Accepted Answer

A) a binding assay. 
B) a biological assay. 
C) an enzyme assay. 
D) an immunological assay. 
E) none of the above 
A) a binding assay. 
B) a biological assay. 
C) an enzyme assay. 
D) an immunological assay. 
E) none of the above

Question 4

Enzymes that hydrolyze the internal peptide bonds (not the peptide bonds of the terminal amino acids)of a protein are classified as

Accepted Answer

A) oxidoreductases. 
B) lyases. 
C) endopeptidases. 
D) nucleases. 
E) exopeptidases. 
A) oxidoreductases. 
B) lyases. 
C) endopeptidases. 
D) nucleases. 
E) exopeptidases.

Question 5

Matching

-In ______ chromatography,a protein mixture must be applied to the column at a low pH so that the proteins will have a net positive charge and bind to the column.

Accepted Answer

A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate 
A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate

Question 6

A variety of chromatographic techniques are available for protein purification.
a.Explain briefly the principle of hydrophobic interaction chromatography.
b.Name three changes that can be made to the eluant that can be used to speed up elution of the protein of interest from a hydrophobic interaction chromatography column.

Accepted Answer

a.The column material is substituted wit

Question 7

Which of the following amino acids would be first to elute at pH 8.0 from an anion-exchange column?

Accepted Answer

A) lysine 
B) alanine 
C) glutamic acid 
D) asparagine 
E) glycine 
A) lysine 
B) alanine 
C) glutamic acid 
D) asparagine 
E) glycine

Question 8

We are able to purify proteins because they differ from each other in various physical or chemical properties.List 5 physicochemical properties of proteins that can be used as basis for their separation.Give a method of separation based on each of these properties (match the method with the property).

Accepted Answer

1.solubility - salting out;2.ionic charg

Question 9

Matching

-______ chromatography is a method of fractionating a protein mixture according to differences in polarity.

Accepted Answer

A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate 
A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate

Question 10

Matching

-In general,proteins are least soluble in water when the pH is close to the ______.

Accepted Answer

A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate 
A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate

Question 11

Although a protein's primary sequence can be inferred from the nucleotide sequence,modifications such as ______ can be determined most easily by tandem mass spectrometry followed by protein database searching.

Accepted Answer

A) phosphorylation 
B) disulfide crosslinks 
C) glycosylation 
D) acetylation 
E) all of the above 
A) phosphorylation 
B) disulfide crosslinks 
C) glycosylation 
D) acetylation 
E) all of the above

Question 12

A technique that can be used to separate proteins based primarily on the presence of non-polar residues on their surface is called

Accepted Answer

A) ion-exchange chromatography. 
B) gel filtration chromatography. 
C) affinity chromatography. 
D) gel electrophoresis. 
E) hydrophobic interaction chromatography. 
A) ion-exchange chromatography. 
B) gel filtration chromatography. 
C) affinity chromatography. 
D) gel electrophoresis. 
E) hydrophobic interaction chromatography.

Question 13

The positive charge on proteins in electrospray ionization mass spectrometry is the result of

Accepted Answer

A) protons fired at the gas-phase protein molecules. 
B) protonated side chains of Asp and Glu residues. 
C) protonated side chains of Arg and Lys residues. 
D) a high pH. 
E) electrons fired at the gas-phase protein molecules. 
A) protons fired at the gas-phase protein molecules. 
B) protonated side chains of Asp and Glu residues. 
C) protonated side chains of Arg and Lys residues. 
D) a high pH. 
E) electrons fired at the gas-phase protein molecules.

Question 14

Proteins are synthesized in vivo by the translation of

Accepted Answer

A) cDNA. 
B) tRNA. 
C) rRNA. 
D) exons. 
E) mRNA. 
A) cDNA. 
B) tRNA. 
C) rRNA. 
D) exons. 
E) mRNA.

Question 15

The salting in of proteins can be explained by:

Accepted Answer

A) salt counter-ions reducing electrostatic attractions between protein molecules. 
B) salt ions reducing the polarity of the solution. 
C) salt ions increasing the hydrophobic interactions. 
D) releasing hydrophobic proteins from nonpolar tissue environments. 
E) hydration of the salt ions reducing solubility of proteins. 
A) salt counter-ions reducing electrostatic attractions between protein molecules. 
B) salt ions reducing the polarity of the solution. 
C) salt ions increasing the hydrophobic interactions. 
D) releasing hydrophobic proteins from nonpolar tissue environments. 
E) hydration of the salt ions reducing solubility of proteins.

Question 16

Matching

-To help prevent denaturation of proteins in solution,steps are taken to avoid _________ and adsorption to surfaces.

Accepted Answer

A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate 
A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate

Question 17

Edman degradation can be used to

Accepted Answer

A) identify the N-terminal amino acid of a polypeptide. 
B) identify the C-terminal amino acid of a polypeptide. 
C) separate the subunits of a multi-subunit protein. 
D) cleave a protein at specific sites. 
E) cleave disulfide bonds within a protein so that the individual polypeptides can be separated. 
A) identify the N-terminal amino acid of a polypeptide. 
B) identify the C-terminal amino acid of a polypeptide. 
C) separate the subunits of a multi-subunit protein. 
D) cleave a protein at specific sites. 
E) cleave disulfide bonds within a protein so that the individual polypeptides can be separated.

Question 18

You have purified the receptor for a hormone by affinity chromatography.During gel filtration chromatography under native conditions the receptor elutes between pyruvate decarboxylase (250 kDa)and glutamine synthetase (620 kDa).During SDS-PAGE,in the absence of reducing agents,the receptor migrates as a single band of approximately 230 kDa.When SDS-PAGE is carried out in the presence of 2-mercaptoethanol the receptor migrates as two bands of approximately 95 and 135 kDa.Explain this result.

Accepted Answer

The receptor is a heterotetramer compose

Question 19

Matching

-One of the reasons the primary structure is important for a protein is that it determines the ______ the molecule adopts in aqueous solutions.

Accepted Answer

A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate 
A)  electrophoresis 
B)  hydrophobic interaction 
C)  enzyme-linked immunosorbent assay 
D)  three-dimensional shape 
E)  N-terminal amino acid
F) negative charge
G) nucleases
H) chromophore
I) foaming 
J) high level expression
K) 2-mercaptoethanol
L) positive charge
M) cation exchange
N) pI
O) chymotrypsin
P) C-terminal amino acid
Q) Sodium dodecyl sulfate

Question 20

One technique commonly used in protein purification is chromatography.
a.Explain briefly the general principle of column chromatography
b.Name four types of chromatography and indicate for each of these types the basis for separation (match types of chromatography with the properties that form the basis for separation).

Accepted Answer

a.In chromatography there are two phases

Exam 5: Proteins: Primary Structure

Proteins are often constructed from multiple segments of 40-200 amino acid residues,commonly called

A fast and common method for determining the protein concentration in column effluent is

You are purifying a nuclease by affinity chromatography.To determine which fractions contain the protein of interest,you test samples of all fractions for their ability to break down DNA.This is an example of

Enzymes that hydrolyze the internal peptide bonds (not the peptide bonds of the terminal amino acids)of a protein are classified as

Matching -In ______ chromatography,a protein mixture must be applied to the column at a low pH so that the proteins will have a net positive charge and bind to the column.

Which of the following amino acids would be first to elute at pH 8.0 from an anion-exchange column?

Matching -______ chromatography is a method of fractionating a protein mixture according to differences in polarity.

Matching -In general,proteins are least soluble in water when the pH is close to the ______.

Although a protein's primary sequence can be inferred from the nucleotide sequence,modifications such as ______ can be determined most easily by tandem mass spectrometry followed by protein database searching.

A technique that can be used to separate proteins based primarily on the presence of non-polar residues on their surface is called

The positive charge on proteins in electrospray ionization mass spectrometry is the result of

Proteins are synthesized in vivo by the translation of

The salting in of proteins can be explained by:

Matching -To help prevent denaturation of proteins in solution,steps are taken to avoid _________ and adsorption to surfaces.

Edman degradation can be used to

Matching -One of the reasons the primary structure is important for a protein is that it determines the ______ the molecule adopts in aqueous solutions.

Introduction to the Chemistry of Life

Water

Nucleotides, nucleic Acids, and Genetic Information

Amino Acids

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Catalysis

Enzyme Kinetics, inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glucose Catabolism

Glycogen Metabolism and Gluconeogenesis

Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

DNA Replication, repair and Recombination

Transcription and Rna Processing

Protein Synthesis

Regulation of Gene Expression

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