Question 1

Disulfide bonds can be cleaved using

Accepted Answer

A) iodoacetate. 
B) dansyl chloride. 
C) 2-mercaptoethanol ($\beta$-M
E) . 
D) trypsin. 
E) phenylisothiocyanate. 
A) iodoacetate. 
B) dansyl chloride. 
C) 2-mercaptoethanol ($\beta$-M
E) . 
D) trypsin. 
E) phenylisothiocyanate. C

Question 2

Matching

-Either dansyl chloride or Edman's reagent can be used to identify the ______ of a protein.

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 E

Question 3

A phylogenetic tree depicts ___________ of proteins.

Accepted Answer

A) folding patterns 
B) hypervariable residues 
C) invariable residues 
D) evolutionary relationships 
E) gene sequences 
A) folding patterns 
B) hypervariable residues 
C) invariable residues 
D) evolutionary relationships 
E) gene sequences D

Question 4

Which of the following substances cannot be used to cleave peptide bonds in polypeptides?

Accepted Answer

A) trypsin 
B) cyanogen bromide 
C) endopeptidases 
D) 2-mercaptoethanol 
E) pepsin 
A) trypsin 
B) cyanogen bromide 
C) endopeptidases 
D) 2-mercaptoethanol 
E) pepsin

Question 5

An enzyme-linked immunosorbent assay requires

Accepted Answer

A) a radioactive substrate. 
B) a radioactive standard for binding to the antibody. 
C) aromatic amino acids. 
D) an antibody that binds the protein of interest. 
E) a catalytic antibody. 
A) a radioactive substrate. 
B) a radioactive standard for binding to the antibody. 
C) aromatic amino acids. 
D) an antibody that binds the protein of interest. 
E) a catalytic antibody.

Question 6

Adding additional salt to a protein solution can cause:

Accepted Answer

A) an increase in solubility called 'salting in'. 
B) a decrease in solubility called 'salting out'. 
C) protein precipitation from solution. 
D) all of the above 
E) none of the above 
A) an increase in solubility called 'salting in'. 
B) a decrease in solubility called 'salting out'. 
C) protein precipitation from solution. 
D) all of the above 
E) none of the above

Question 7

A protein that has had few changes in its amino acid sequence over evolutionary history is labeled

Accepted Answer

A) a fibrinopeptide. 
B) evolutionarily conserved. 
C) random. 
D) a product of pseudogenes. 
E) phylogenetic. 
A) a fibrinopeptide. 
B) evolutionarily conserved. 
C) random. 
D) a product of pseudogenes. 
E) phylogenetic.

Question 8

A radioimmunoassay requires

Accepted Answer

A) an enzyme-linked antibody. 
B) a coupled enzymatic reaction. 
C) a radiolabeled antibody. 
D) a catalytic antibody. 
E) a radiolabeled standard protein that is used to compete for binding to the antibody. 
A) an enzyme-linked antibody. 
B) a coupled enzymatic reaction. 
C) a radiolabeled antibody. 
D) a catalytic antibody. 
E) a radiolabeled standard protein that is used to compete for binding to the antibody.

Question 9

Five graduate students prepare extracts from 5 different tissues.Each student measures the total amount of alcohol dehydrogenase and the total amount of protein in his or her extract.Which extract has the highest specific activity?

Accepted Answer

The answer of Five graduate students prepare extracts from 5...

Question 10

Matching

-In SDS-PAGE,disulfide-linked polypeptides can be separated after reacting the protein first with ______.

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

Which statement about insulin is correct?

Accepted Answer

A) Insulin is composed of two polypeptides,the A chain and the B chain. 
B) Insulin contains an intrachain disulfide bond. 
C) Insulin contains interchain disulfide bonds. 
D) The A chain and the B chain of insulin are encoded by a single gene. 
E) All of the above are correct. 
A) Insulin is composed of two polypeptides,the A chain and the B chain. 
B) Insulin contains an intrachain disulfide bond. 
C) Insulin contains interchain disulfide bonds. 
D) The A chain and the B chain of insulin are encoded by a single gene. 
E) All of the above are correct.

Question 12

The peptide Leu─Cys─Arg─Ser─Gln─Met is subjected to Edman degradation.In the first cycle the peptide first reacts with phenylisothiocyanate under basic conditions.The product of this reaction is incubated with anhydrous trifluoroacetic acid and subsequently with an aqueous acid.What are the products generated in the first cycle.

Accepted Answer

A) PTH─Leu,PTH─Cys,PTH─Arg,PTH─Ser,PTH─Gln,and PTH─Met 
B) PTH─Leu─Cys─Arg─Ser─Gln─Met 
C) PTH─Met and Leu─Cys─Arg─Ser─Gln─Met 
D) PTH─Leu─Cys and PTH─Arg─Ser─Gln─Met 
E) PTH─Leu and Cys─Arg─Ser─Gln─Met 
A) PTH─Leu,PTH─Cys,PTH─Arg,PTH─Ser,PTH─Gln,and PTH─Met 
B) PTH─Leu─Cys─Arg─Ser─Gln─Met 
C) PTH─Met and Leu─Cys─Arg─Ser─Gln─Met 
D) PTH─Leu─Cys and PTH─Arg─Ser─Gln─Met 
E) PTH─Leu and Cys─Arg─Ser─Gln─Met

Question 13

You are trying to separate five proteins,which are listed below,by gel filtration chromatography.Which of the proteins will elute first from the column?

Accepted Answer

A) cytochrome c (12 kDa) 
B) RNA polymerase (99 kDa) 
C) glutamine synthetase (621 kDa) 
D) interferon-$\gamma$ (34 kDa) 
E) hemoglobin (62 kDa) 
A) cytochrome c (12 kDa) 
B) RNA polymerase (99 kDa) 
C) glutamine synthetase (621 kDa) 
D) interferon-$\gamma$ (34 kDa) 
E) hemoglobin (62 kDa)

Question 14

In two homologous proteins,which residue is most likely to replace a Glu residue as a conservative substitution?

Accepted Answer

A) Asp 
B) Trp 
C) Met 
D) Ile 
E) Lys 
A) Asp 
B) Trp 
C) Met 
D) Ile 
E) Lys

Question 15

A technique that can be used to separate proteins based primarily on their pI is called

Accepted Answer

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

Question 16

___________ is an example of a very slowly evolving protein.

Accepted Answer

A) Histone H4 
B) Hemoglobin 
C) Cytochrome c 
D) Fibrinopeptides 
E) none of the above 
A) Histone H4 
B) Hemoglobin 
C) Cytochrome c 
D) Fibrinopeptides 
E) none of the above

Question 17

Proteins can vary in size from approximately 40 to 34,000 amino acids.
a.Why is there a lower limit to the size of proteins?
b.Why is there an upper limit to the size of polypeptides?

Accepted Answer

a.Polypeptides shorter than 40 residues

Question 18

Protein sequences are customarily 'reconstructed' from sequenced fragments because

Accepted Answer

A) protein purification invariably results in the fragmentation of the protein of interest. 
B) proteins are naturally and inevitably cleaved by proteolytic enzymes. 
C) proteins are composed of multiple subunits. 
D) large polypeptides cannot be directly sequenced. 
E) all of the above 
A) protein purification invariably results in the fragmentation of the protein of interest. 
B) proteins are naturally and inevitably cleaved by proteolytic enzymes. 
C) proteins are composed of multiple subunits. 
D) large polypeptides cannot be directly sequenced. 
E) all of the above

Question 19

Which of the following 'assays' would be most specific for a particular protein?

Accepted Answer

A) Bradford assay 
B) UV absorptivity 
C) radioimmunoassay 
D) molar absorptivity 
E) amino acid analysis 
A) Bradford assay 
B) UV absorptivity 
C) radioimmunoassay 
D) molar absorptivity 
E) amino acid analysis

Question 20

The vast majority of polypeptides contain between ______ amino acid residues.

Accepted Answer

A) 10 and 50 
B) 50 and 100 
C) 100 and 1000 
D) 1000 and 2000 
E) 2000 and 34,000 
A) 10 and 50 
B) 50 and 100 
C) 100 and 1000 
D) 1000 and 2000 
E) 2000 and 34,000

Exam 5: Proteins: Primary Structure

Disulfide bonds can be cleaved using

Matching -Either dansyl chloride or Edman's reagent can be used to identify the ______ of a protein.

A phylogenetic tree depicts ___________ of proteins.

Which of the following substances cannot be used to cleave peptide bonds in polypeptides?

An enzyme-linked immunosorbent assay requires

Adding additional salt to a protein solution can cause:

A protein that has had few changes in its amino acid sequence over evolutionary history is labeled

A radioimmunoassay requires

Five graduate students prepare extracts from 5 different tissues.Each student measures the total amount of alcohol dehydrogenase and the total amount of protein in his or her extract.Which extract has the highest specific activity?

Matching -In SDS-PAGE,disulfide-linked polypeptides can be separated after reacting the protein first with ______.

Which statement about insulin is correct?

You are trying to separate five proteins,which are listed below,by gel filtration chromatography.Which of the proteins will elute first from the column?

In two homologous proteins,which residue is most likely to replace a Glu residue as a conservative substitution?

A technique that can be used to separate proteins based primarily on their pI is called

___________ is an example of a very slowly evolving protein.

Proteins can vary in size from approximately 40 to 34,000 amino acids. a.Why is there a lower limit to the size of proteins? b.Why is there an upper limit to the size of polypeptides?

Protein sequences are customarily 'reconstructed' from sequenced fragments because

Which of the following 'assays' would be most specific for a particular protein?

The vast majority of polypeptides contain between ______ amino acid residues.

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

Filters