Question 1

Proteins will normally exhibit minimum solubility in aqueous solutions at

Accepted Answer

A)  a pH values above Pi. 
B)  a pH values below Pi. 
C)  a pH value = Pi. 
D)  low salt concentrations. 
E)  none of the above 
A)  a pH values above Pi. 
B)  a pH values below Pi. 
C)  a pH value = Pi. 
D)  low salt concentrations. 
E)  none of the above

Question 2

All of the following bond types are significant for the maintenance of the secondary, tertiary, and quaternary structure of enzymes or proteins EXCEPT

Accepted Answer

A)  hydrophobic interactions. 
B)  disulfide bonds. 
C)  ester bonds. 
D)  hydrogen bonds. 
E)  electrostatic interactions. 
A)  hydrophobic interactions. 
B)  disulfide bonds. 
C)  ester bonds. 
D)  hydrogen bonds. 
E)  electrostatic interactions.

Question 3

Denaturation of a protein usually involves the disruption of all of the following types of interactions EXCEPT

Accepted Answer

A)  Van Der Waals interactions. 
B)  peptide bonds. 
C)  hydrogen bonds. 
D)  ionic interactions. 
E)  hydrophobic interactions. 
A)  Van Der Waals interactions. 
B)  peptide bonds. 
C)  hydrogen bonds. 
D)  ionic interactions. 
E)  hydrophobic interactions.

Question 4

A major force that contributes to the conformation of proteins and, in globular proteins, occurs primarily in their interior is

Accepted Answer

A)  hydrogen bonds. 
B)  charged dipoles. 
C)  hydrophobic interactions. 
D)  disulfide bridges. 
E)  hydration by water. 
A)  hydrogen bonds. 
B)  charged dipoles. 
C)  hydrophobic interactions. 
D)  disulfide bridges. 
E)  hydration by water.

Question 5

Which of the following amino acids possesses an uncharged side-chain at pH 7.0?

Accepted Answer

A)  lysine 
B)  aspartate 
C)  arginine 
D)  serine 
E)  glutamate 
A)  lysine 
B)  aspartate 
C)  arginine 
D)  serine 
E)  glutamate

Question 6

Which of the following statements about protein structure is correct?

Accepted Answer

A)  The alpha-helix conformation is stabilized by hydrophobic interactions. 
B)  The beta-sheet conformation is rarely found in globular proteins. 
C)  The folding of a polypeptide into a globular structure results in an interior enriched with hydrophobic amino acids. 
D)  The primary structure does not influence the native tertiary structure. 
E)  The subunits of proteins with quaternary structure associate through covalent bonds. 
A)  The alpha-helix conformation is stabilized by hydrophobic interactions. 
B)  The beta-sheet conformation is rarely found in globular proteins. 
C)  The folding of a polypeptide into a globular structure results in an interior enriched with hydrophobic amino acids. 
D)  The primary structure does not influence the native tertiary structure. 
E)  The subunits of proteins with quaternary structure associate through covalent bonds.

Question 7

Which of the following is a kind of physical/chemical interaction of major quantitative importance in the overall structure of most globular proteins and occurs chiefly in the interior areas of the molecule?

Accepted Answer

A)  Disulfide bridges. 
B)  Hydrophobic bonds. 
C)  Amide linkages between amino acid sidechains. 
D)  Ester linkages between sidechains of acidic and alcoholic amino acids. 
E)  Hydrogen bonds to water molecules. 
A)  Disulfide bridges. 
B)  Hydrophobic bonds. 
C)  Amide linkages between amino acid sidechains. 
D)  Ester linkages between sidechains of acidic and alcoholic amino acids. 
E)  Hydrogen bonds to water molecules.

Question 8

Which of the following describes the side chain of phenylalanine?

Accepted Answer

A)  contains a sulfhydryl group 
B)  contains an alcoholic group 
C)  contains an branched chain hydrocarbon 
D)  doesn't have a side chain 
E)  contains an aromatic ring 
A)  contains a sulfhydryl group 
B)  contains an alcoholic group 
C)  contains an branched chain hydrocarbon 
D)  doesn't have a side chain 
E)  contains an aromatic ring

Question 9

Which of the following describes the side chain of leucine?

Accepted Answer

A)  contains a sulfhydryl group 
B)  contains an alcoholic group 
C)  contains an branched chain hydrocarbon 
D)  doesn't have a side chain 
E)  contains an acidic group 
A)  contains a sulfhydryl group 
B)  contains an alcoholic group 
C)  contains an branched chain hydrocarbon 
D)  doesn't have a side chain 
E)  contains an acidic group

Question 10

Which of the following peptides would be partially hydrolyzed by the enzyme trypsin?

Accepted Answer

A)  glu-ala-tyr-lys 
B)  ser-asn-ser-ser 
C)  pro-gly-thr-ala 
D)  gly-arg-gln-trp 
E)  None of the other answers is correct. 
A)  glu-ala-tyr-lys 
B)  ser-asn-ser-ser 
C)  pro-gly-thr-ala 
D)  gly-arg-gln-trp 
E)  None of the other answers is correct.

Question 11

All of the following statements about protein structure are correct EXCEPT which one?

Accepted Answer

A)  Other than peptide bonds, hydrogen bonding is the most important interaction in pleated sheet and alpha-helical structures. 
B)  The peptide bond is one kind of amide linkage. 
C)  The native state of a protein is the least stable form under cell conditions and accordingly is easily denatured. 
D)  In the alpha helix, the amino acid side chains project out from the coiled backbone of the polypeptide chain. 
E)  Globular proteins often contain a pocket or groove into which a prosthetic group or substrate can fit. 
A)  Other than peptide bonds, hydrogen bonding is the most important interaction in pleated sheet and alpha-helical structures. 
B)  The peptide bond is one kind of amide linkage. 
C)  The native state of a protein is the least stable form under cell conditions and accordingly is easily denatured. 
D)  In the alpha helix, the amino acid side chains project out from the coiled backbone of the polypeptide chain. 
E)  Globular proteins often contain a pocket or groove into which a prosthetic group or substrate can fit.

Question 12

The peptide bond has all of the following characteristics EXCEPT

Accepted Answer

A)  planarity. 
B)  freedom to rotate. 
C)  polarity. 
D)  greater stability in TRANS configuration. 
E)  partial double bond character. 
A)  planarity. 
B)  freedom to rotate. 
C)  polarity. 
D)  greater stability in TRANS configuration. 
E)  partial double bond character.

Question 13

All of the following amino acids are required as precursors for collagen synthesis EXCEPT

Accepted Answer

A)  lysine. 
B)  glycine. 
C)  proline. 
D)  hydroxyproline. 
E)  phenylalanine. 
A)  lysine. 
B)  glycine. 
C)  proline. 
D)  hydroxyproline. 
E)  phenylalanine.

Question 14

Which of the following is a characteristic of the amino acid composition of a protein which has an isoelectric pH (pI) of 9.5 ?

Accepted Answer

A)  no basic amino acids 
B)  no acidic amino acids 
C)  no neutral amino acids 
D)  more basic than acidic amino acids 
E)  more acidic than basic amino acids 
A)  no basic amino acids 
B)  no acidic amino acids 
C)  no neutral amino acids 
D)  more basic than acidic amino acids 
E)  more acidic than basic amino acids

Question 15

The primary sequence of proteins is best described by the statement that proteins

Accepted Answer

A)  contain amino acids. 
B)  include all the nitrogen compounds of tissues. 
C)  are salts of amino acids linked with one another. 
D)  are polymers formed by hydrogen bonding between the amino acids. 
E)  are polymers formed by amide linkages between the carboxyl and alpha-amino groups of alpha-amino acids. 
A)  contain amino acids. 
B)  include all the nitrogen compounds of tissues. 
C)  are salts of amino acids linked with one another. 
D)  are polymers formed by hydrogen bonding between the amino acids. 
E)  are polymers formed by amide linkages between the carboxyl and alpha-amino groups of alpha-amino acids.

Question 16

If gly has a positive charge in a buffer at pH 1, then gly-gly-gly in the same buffer should have which of the following charges?

Accepted Answer

A) +3 
B) +2 
C) +1 
D) -1 
E) -2 
A) +3 
B) +2 
C) +1 
D) -1 
E) -2

Question 17

Chaperone proteins help nascent proteins achieve correct folding. What other function do they serve?

Accepted Answer

A)  Addition of prosthetic groups 
B)  Cleavage of zymogens 
C)  Protein refolding after crossing a membrane 
D)  Stabilization of tetrameric conformation 
E)  Targeting to organelles 
A)  Addition of prosthetic groups 
B)  Cleavage of zymogens 
C)  Protein refolding after crossing a membrane 
D)  Stabilization of tetrameric conformation 
E)  Targeting to organelles

Question 18

Collagen is a protein whose conformation is characterized by

Accepted Answer

A)  a triple helix. 
B)  a double alpha-helix. 
C)  antiparallel beta-sheet regions. 
D)  mostly random coil regions. 
E)  the lack of any stable conformation. 
A)  a triple helix. 
B)  a double alpha-helix. 
C)  antiparallel beta-sheet regions. 
D)  mostly random coil regions. 
E)  the lack of any stable conformation.

Question 19

We have treated a protein with chymotrypsin (cleaves at aromatic amino acid residues) and have isolated a polypeptide fragment produced during the chymotryptic digestion. The amino acid composition of the polypeptide was found to be amino acid moles/mole polypeptide lysine (lys)2 glycine (gly) 1 serine (ser)1 phenylalanine (phe)1. The N-terminal amino acid, determined by the dansylation procedure, was serine. Treatment of the polypeptide with trypsin (cleaves at basic amino acid residues) gave two dipeptides plus free phenylalanine What is the amino acid sequence of this polypeptide?

Accepted Answer

A)  ser-gly-lys-phe-lys 
B)  gly-lys-ser-lys-phe 
C)  ser-gly-lys-lys-phe 
D)  phe-lys-gly-ser-lys 
E)  ser-lys-gly-lys-phe 
A)  ser-gly-lys-phe-lys 
B)  gly-lys-ser-lys-phe 
C)  ser-gly-lys-lys-phe 
D)  phe-lys-gly-ser-lys 
E)  ser-lys-gly-lys-phe

Question 20

Which of the following statements describing the alpha_helix is NOT correct?

Accepted Answer

A)  It is found in globular proteins in both aqueous and membrane environments. 
B)  It may have a surface that is amphipathic (hydrophobic on one side and hydrophilic on the other). 
C)  Prolines are positioned at intervals of three or four residues. 
D)  Side chains (R groups) pointing away from the core of the helix may stabilize its conformation. 
E)  There are about 3.5 amino acid residues in each turn. 
A)  It is found in globular proteins in both aqueous and membrane environments. 
B)  It may have a surface that is amphipathic (hydrophobic on one side and hydrophilic on the other). 
C)  Prolines are positioned at intervals of three or four residues. 
D)  Side chains (R groups) pointing away from the core of the helix may stabilize its conformation. 
E)  There are about 3.5 amino acid residues in each turn.

Exam 3: Protein I: Composition and Structure

Proteins will normally exhibit minimum solubility in aqueous solutions at

All of the following bond types are significant for the maintenance of the secondary, tertiary, and quaternary structure of enzymes or proteins EXCEPT

Denaturation of a protein usually involves the disruption of all of the following types of interactions EXCEPT

A major force that contributes to the conformation of proteins and, in globular proteins, occurs primarily in their interior is

Which of the following amino acids possesses an uncharged side-chain at pH 7.0?

Which of the following statements about protein structure is correct?

Which of the following is a kind of physical/chemical interaction of major quantitative importance in the overall structure of most globular proteins and occurs chiefly in the interior areas of the molecule?

Which of the following describes the side chain of phenylalanine?

Which of the following describes the side chain of leucine?

Which of the following peptides would be partially hydrolyzed by the enzyme trypsin?

All of the following statements about protein structure are correct EXCEPT which one?

The peptide bond has all of the following characteristics EXCEPT

All of the following amino acids are required as precursors for collagen synthesis EXCEPT

Which of the following is a characteristic of the amino acid composition of a protein which has an isoelectric pH (pI) of 9.5 ?

The primary sequence of proteins is best described by the statement that proteins

If gly has a positive charge in a buffer at pH 1, then gly-gly-gly in the same buffer should have which of the following charges?

Chaperone proteins help nascent proteins achieve correct folding. What other function do they serve?

Collagen is a protein whose conformation is characterized by

Which of the following statements describing the alpha_helix is NOT correct?

Eukaryotic Cell Structure

DNA and RNA: Composition and Structure

DNA Replication, Recombination, and Repair

RNA: Transcription and Rna Processing

Protein Synthesis: Translation and Posttranslational Modifications

Recombinant Dna and Biotechnology

Regulation of Gene Expression

Protein II: Structure-Function Relationships in Protein Families

Enzymes: Classification, Kinetics, and Control

The Cytochromes P450 and Nitric Oxide Synthases

Biological Membranes: Structure and Membrane Transport

Fundamentals of Signal Transduction

Bioenergetics and Oxidative Metabolism

Carbohydrate Metabolism I: Major Metabolic Pathways and Their Control

Carbohydrate Metabolism II: Special Pathways and Glycoconjugates

Lipid Metabolism I: Synthesis, Storage, and Utilization of Fatty Acids and Triacylglycerols

Lipid Metabolism II: Pathways of Metabolism of Special Lipids

Amino Acid Metabolism

Purine and Pyrimidine Nucleotide Metabolism

Metabolic Interrelationships

Biochemistry of Hormones

Molecular Cell Biology

Cell Cycle, Programmed Cell Death, and Cancer

Digestion and Absorption of Basic Nutritional Constituents

Digestion and Absorption of Basic Nutritional Constituents

Principles of Nutrition I and II

Filters