Question 1

What is the isoelectric point of cysteine? (pK1 = 1.96, pK2 = 8.18 and pK3 = 10.28).

Accepted Answer

A)  1.96 
B)  5.07 
C)  8.18 
D)  9.23 
E)  10.28 
A)  1.96 
B)  5.07 
C)  8.18 
D)  9.23 
E)  10.28

Question 2

The formation of a peptide bond between two amino acids

Accepted Answer

A)  creates partial double-bond character among three atoms. 
B)  permits unrestricted rotations about each chemical bond. 
C)  places the alpha-carbons in the "centers" of two different planes. 
D)  retains the chemical properties of the typical ester bond. 
A)  creates partial double-bond character among three atoms. 
B)  permits unrestricted rotations about each chemical bond. 
C)  places the alpha-carbons in the "centers" of two different planes. 
D)  retains the chemical properties of the typical ester bond.

Question 3

Which of the following solutions would be most likely to completely unfold a protein?

Accepted Answer

A)  a dilute phosphate buffer at 100 degrees Celsius 
B)  5M guanidine hydrochloride 
C)  one percent sodium dodecyl sulfate 
D)  five percent trichloroacetic acid 
E)  twenty percent acetone 
A)  a dilute phosphate buffer at 100 degrees Celsius 
B)  5M guanidine hydrochloride 
C)  one percent sodium dodecyl sulfate 
D)  five percent trichloroacetic acid 
E)  twenty percent acetone

Question 4

Which of the following sections of a polypeptide chain have amino acid side chains, all of which are capable of forming hydrogen bonds?

Accepted Answer

A)  leu-val-phe 
B)  cys-his-ala 
C)  ile-ser-trp 
D)  val-arg-pro 
E)  asp-lys-ser 
A)  leu-val-phe 
B)  cys-his-ala 
C)  ile-ser-trp 
D)  val-arg-pro 
E)  asp-lys-ser

Question 5

Each of the following statements about the anti-parallel pleated sheet is true EXCEPT which one?

Accepted Answer

A)  Adjacent polypeptide chains run in the same direction. 
B)  Adjacent polypeptide chains run in opposite directions. 
C)  It gives a characteristic x-ray diffraction pattern. 
D)  It gives a characteristic circular dichroism curve. 
E)  amino acids with short side-chains promote its formation. 
A)  Adjacent polypeptide chains run in the same direction. 
B)  Adjacent polypeptide chains run in opposite directions. 
C)  It gives a characteristic x-ray diffraction pattern. 
D)  It gives a characteristic circular dichroism curve. 
E)  amino acids with short side-chains promote its formation.

Question 6

Which of the following statements about cystine is true?

Accepted Answer

A)  cystine is two cysteine molecules covalently attached by a disulfide bridge 
B)  cystine is formed by the reduction of two cysteines 
C)  cystine is a dipeptide 
D)  cystine is a tripeptide 
E)  cystine forms disulfide bridges with methionine 
A)  cystine is two cysteine molecules covalently attached by a disulfide bridge 
B)  cystine is formed by the reduction of two cysteines 
C)  cystine is a dipeptide 
D)  cystine is a tripeptide 
E)  cystine forms disulfide bridges with methionine

Question 7

Which of the following techniques for purifying proteins relies on differences in the sizes of proteins?

Accepted Answer

A)  Ion exchange chromatography 
B)  Isoelectric precipitation 
C)  Salting out 
D)  Gel permeation chromatography 
E)  Zonal electrophoresis 
A)  Ion exchange chromatography 
B)  Isoelectric precipitation 
C)  Salting out 
D)  Gel permeation chromatography 
E)  Zonal electrophoresis

Question 8

What leads to "superfolds"?

Accepted Answer

A)  Evolutionary development 
B)  Ratio of a-helices to b-pleated sheets 
C)  Similar function 
D)  Similar primary structure 
E)  Thermodynamic stability 
A)  Evolutionary development 
B)  Ratio of a-helices to b-pleated sheets 
C)  Similar function 
D)  Similar primary structure 
E)  Thermodynamic stability

Question 9

Which of the following tripeptides will move anodically (positive electrode) during electrophoresis at pH 5?

Accepted Answer

A)  asp-his-lys 
B)  arg-pro-gly 
C)  asn-glu-val 
D)  gln-his-arg 
A)  asp-his-lys 
B)  arg-pro-gly 
C)  asn-glu-val 
D)  gln-his-arg

Question 10

An amino acid containing an amide function in its side chain

Accepted Answer

A)  proline. 
B)  lysine. 
C)  arginine. 
D)  asparagine. 
E)  histidine. 
A)  proline. 
B)  lysine. 
C)  arginine. 
D)  asparagine. 
E)  histidine.

Question 11

Which of the following amino acid substitutions (as by mutation) in the beta chain of hemoglobin would be LEAST likely to affect the three-dimensional structure and biological function of the molecule?

Accepted Answer

A)  Arg for Tyr 
B)  Trp for Ile 
C)  Gln for Phe 
D)  Cys for Gly 
E)  Ile for Leu 
A)  Arg for Tyr 
B)  Trp for Ile 
C)  Gln for Phe 
D)  Cys for Gly 
E)  Ile for Leu

Question 12

The nitrogen content of proteins by weight is about

Accepted Answer

A)  5%. 
B)  6.25%. 
C)  16%. 
D)  30%. 
E)  40%. 
A)  5%. 
B)  6.25%. 
C)  16%. 
D)  30%. 
E)  40%.

Question 13

Which of the following techniques is best suited for the determination of the subunit molecular weight of an oligomeric protein?

Accepted Answer

A)  circular dichroism 
B)  sedimentation velocity ultracentrifugation 
C)  SDS polyacrylamide gel electrophoresis 
D)  gel chromatography in dilute buffer 
E)  cellulose acetate electrophoresis 
A)  circular dichroism 
B)  sedimentation velocity ultracentrifugation 
C)  SDS polyacrylamide gel electrophoresis 
D)  gel chromatography in dilute buffer 
E)  cellulose acetate electrophoresis

Question 14

How many carbon and nitrogen atoms are there, respectively, in a single turn of an alpha-helix?

Accepted Answer

A) 6 5 
B) 7 5 
C) 7 4 
D) 6 4 
E) 5 7 
A) 6 5 
B) 7 5 
C) 7 4 
D) 6 4 
E) 5 7

Question 15

Which one of the following is a characteristic of the amino acid composition of a protein having an isoelectric pH (pI) of 4?

Accepted Answer

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

Question 16

All of the following statements about the peptide bond are true EXCEPT which one?

Accepted Answer

A)  Peptide bonds can be formed by any of the naturally occurring amino acids. 
B)  There is free rotation around the peptide bond. 
C)  The peptide bond contains a carbonyl group. 
D)  The nitrogen atom of the peptide bond does not contain a plus charge below pH 5.0. 
E)  In proteins, not all of the amino groups occur in peptide bonds. 
A)  Peptide bonds can be formed by any of the naturally occurring amino acids. 
B)  There is free rotation around the peptide bond. 
C)  The peptide bond contains a carbonyl group. 
D)  The nitrogen atom of the peptide bond does not contain a plus charge below pH 5.0. 
E)  In proteins, not all of the amino groups occur in peptide bonds.

Question 17

Covalent modifications of collagen include all of the following EXCEPT

Accepted Answer

A)  hydroxylation of proline and lysine. 
B)  glycosylation of hydroxylysine. 
C)  oxidation of lysine or hydroxylysine. 
D)  formation of covalent cross-links by virtue of the reactivity of allysine or hydroxyallysine aldehyde groups. 
E)  stabilization of the mature fiber with disulfide bonds. 
A)  hydroxylation of proline and lysine. 
B)  glycosylation of hydroxylysine. 
C)  oxidation of lysine or hydroxylysine. 
D)  formation of covalent cross-links by virtue of the reactivity of allysine or hydroxyallysine aldehyde groups. 
E)  stabilization of the mature fiber with disulfide bonds.

Question 18

Indicate the type of bond principally responsible for the SECONDARY structure of proteins

Accepted Answer

A)  hydrogen bonds. 
B)  hydrophilic bonds. 
C)  hydrophobic bonds. 
D)  electrostatic bonds. 
E)  covalent bonds. 
A)  hydrogen bonds. 
B)  hydrophilic bonds. 
C)  hydrophobic bonds. 
D)  electrostatic bonds. 
E)  covalent bonds.

Question 19

SDS/polyacrylamide gel electrophoresis separates proteins based on

Accepted Answer

A)  size of the polypeptide chain 
B)  net charge of the native protein 
C)  net charge of the denatured protein 
D)  all of the above 
E)  none of the above 
A)  size of the polypeptide chain 
B)  net charge of the native protein 
C)  net charge of the denatured protein 
D)  all of the above 
E)  none of the above

Question 20

What is the nature of the usual linkage between nucleic acids and proteins in nucleoproteins?

Accepted Answer

A)  Hydrogen bonding. 
B)  Covalent ester formation between phosphoric acid of nucleic acids and basic amino acids of proteins. 
C)  Ionic linkages between phosphoric acid of nucleic acids and basic amino acids of proteins. 
D)  Van der Waals interactions between bases of nucleic acids and side chains of amino acids of protein. 
E)  A mixture of covalent linkages and hydrogen bonding. 
A)  Hydrogen bonding. 
B)  Covalent ester formation between phosphoric acid of nucleic acids and basic amino acids of proteins. 
C)  Ionic linkages between phosphoric acid of nucleic acids and basic amino acids of proteins. 
D)  Van der Waals interactions between bases of nucleic acids and side chains of amino acids of protein. 
E)  A mixture of covalent linkages and hydrogen bonding.

Exam 3: Protein I: Composition and Structure

What is the isoelectric point of cysteine? (pK1 = 1.96, pK2 = 8.18 and pK3 = 10.28).

The formation of a peptide bond between two amino acids

Which of the following solutions would be most likely to completely unfold a protein?

Which of the following sections of a polypeptide chain have amino acid side chains, all of which are capable of forming hydrogen bonds?

Each of the following statements about the anti-parallel pleated sheet is true EXCEPT which one?

Which of the following statements about cystine is true?

Which of the following techniques for purifying proteins relies on differences in the sizes of proteins?

What leads to "superfolds"?

Which of the following tripeptides will move anodically (positive electrode) during electrophoresis at pH 5?

An amino acid containing an amide function in its side chain

Which of the following amino acid substitutions (as by mutation) in the beta chain of hemoglobin would be LEAST likely to affect the three-dimensional structure and biological function of the molecule?

The nitrogen content of proteins by weight is about

Which of the following techniques is best suited for the determination of the subunit molecular weight of an oligomeric protein?

How many carbon and nitrogen atoms are there, respectively, in a single turn of an alpha-helix?

Which one of the following is a characteristic of the amino acid composition of a protein having an isoelectric pH (pI) of 4?

All of the following statements about the peptide bond are true EXCEPT which one?

Covalent modifications of collagen include all of the following EXCEPT

Indicate the type of bond principally responsible for the SECONDARY structure of proteins

SDS/polyacrylamide gel electrophoresis separates proteins based on

What is the nature of the usual linkage between nucleic acids and proteins in nucleoproteins?

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