Question 1

Silk fibers consist of ____ proteins consisting of alternating ____ and ____ or ____ residues.

Accepted Answer

A)  fibroin; glycine; proline; leucine 
B)  α-keratin; alanine; glycine; serine 
C)  fibroin; glycine; alanine; threonine 
D)  β-keratin; cysteine; alanine; proline 
E)  fibroin; glycine; alanine; serine 
A)  fibroin; glycine; proline; leucine 
B)  α-keratin; alanine; glycine; serine 
C)  fibroin; glycine; alanine; threonine 
D)  β-keratin; cysteine; alanine; proline 
E)  fibroin; glycine; alanine; serine

Question 2

Secondary and higher orders of structure are determined by all EXCEPT:

Accepted Answer

A)  hydrophobic interactions. 
B)  ionic bonds. 
C)  van der Waals forces. 
D)  hydrogen bonds. 
E)  peptide bonds. 
A)  hydrophobic interactions. 
B)  ionic bonds. 
C)  van der Waals forces. 
D)  hydrogen bonds. 
E)  peptide bonds.

Question 3

____ is an example of a disulfide-rich protein.

Accepted Answer

A)  Insulin 
B)  Glyceraldehyde-3-phosphate dehydrogenase 
C)  Hemoglobin 
D)  Triose phosphate isomerase 
E)  All are true. 
A)  Insulin 
B)  Glyceraldehyde-3-phosphate dehydrogenase 
C)  Hemoglobin 
D)  Triose phosphate isomerase 
E)  All are true.

Question 4

Which of the following amino acids would generally not be found in an α-helix?

Accepted Answer

A)  Ala 
B)  His 
C)  Leu 
D)  Ser 
E)  Met 
A)  Ala 
B)  His 
C)  Leu 
D)  Ser 
E)  Met

Question 5

Amino acid side chains capable of forming hydrogen bonds are usually located on the protein ____ and form hydrogen bonds primarily with the ____.

Accepted Answer

A)  surface, water solvent 
B)  interior, water solvent 
C)  surface, other amino acid side chains 
D)  interior, other amino acid side chains 
E)  all are true 
A)  surface, water solvent 
B)  interior, water solvent 
C)  surface, other amino acid side chains 
D)  interior, other amino acid side chains 
E)  all are true

Question 6

The "permanent" part of adding wave in hair is primarily due to:

Accepted Answer

A)  rearrangement of hydrogen bonds between hair fibers. 
B)  reestablishment of new ionic interactions between hair fibers. 
C)  breaking and reforming peptide bonds in the hair polypeptides. 
D)  rearrangement of hydrophobic interactions in hair fibers. 
E)  reduction and re-oxidation of disulfide bonds in hair fibers. 
A)  rearrangement of hydrogen bonds between hair fibers. 
B)  reestablishment of new ionic interactions between hair fibers. 
C)  breaking and reforming peptide bonds in the hair polypeptides. 
D)  rearrangement of hydrophobic interactions in hair fibers. 
E)  reduction and re-oxidation of disulfide bonds in hair fibers.

Question 7

Prolyl hydroxylase has all of the following characteristics EXCEPT:

Accepted Answer

A)  requires citric acid. 
B)  is activated by Fe2+. 
C)  hydroxylates proline residues in proteins. 
D)  requires molecular oxygen. 
E)  requires α-ketoglutarate. 
A)  requires citric acid. 
B)  is activated by Fe2+. 
C)  hydroxylates proline residues in proteins. 
D)  requires molecular oxygen. 
E)  requires α-ketoglutarate.

Question 8

In hemoglobin, a ____ protein, the space between the helices is filled efficiently and tightly with mostly ____ amino acid chains and with ____ side chains facing the outside of the protein structure.

Accepted Answer

A)  globular, hydrophobic, polar 
B)  globular, polar, nonpolar 
C)  fibrous, hydrophobic, nonpolar 
D)  fibrous, polar, nonpolar 
E)  none are true 
A)  globular, hydrophobic, polar 
B)  globular, polar, nonpolar 
C)  fibrous, hydrophobic, nonpolar 
D)  fibrous, polar, nonpolar 
E)  none are true

Question 9

All of the information necessary for folding the peptide chain into its "native" structure is contained in the ____ of the peptide.

Accepted Answer

A)  amino acid sequence 
B)  amino acid composition 
C)  configuration 
D)  amino acid side chain charges 
E)  all are true 
A)  amino acid sequence 
B)  amino acid composition 
C)  configuration 
D)  amino acid side chain charges 
E)  all are true

Question 10

Polylysine is a random coil when the pH is less than 11, while it forms an α-helix if the pH is raised to greater than 12. This is because at pH 12:

Accepted Answer

A)  the lysine residues are negatively charged which electrostatically stabilizes the helix. 
B)  the positive charges on the lysine residues stabilizes the α-helix. 
C)  the lysine residues are neutral which eliminates electrostatic repulsion between the R groups. 
D)  the high concentration of OH− ions in solution reduces the electrostatic repulsion between the R-groups. 
E)  the lysine side chain changes configuration with pH. 
A)  the lysine residues are negatively charged which electrostatically stabilizes the helix. 
B)  the positive charges on the lysine residues stabilizes the α-helix. 
C)  the lysine residues are neutral which eliminates electrostatic repulsion between the R groups. 
D)  the high concentration of OH− ions in solution reduces the electrostatic repulsion between the R-groups. 
E)  the lysine side chain changes configuration with pH.

Question 11

The unique composition of collagen is accommodated in a structure called a(n):

Accepted Answer

A)  β-pleated sheet. 
B)  triple helix. 
C)  helix-turn-helix motif. 
D)  coiled coils. 
E)  all are true. 
A)  β-pleated sheet. 
B)  triple helix. 
C)  helix-turn-helix motif. 
D)  coiled coils. 
E)  all are true.

Question 12

α-Keratin has all of the following characteristics EXCEPT:

Accepted Answer

A)  primary component in hair, claws, fingernails, and horns of animals. 
B)  consists of four helical strands arranged as twisted pairs of two-stranded coiled coils. 
C)  has associated hydrophobic strips on the two coiled coils. 
D)  presence of properly placed polar amino acids help to solubilize α-keratin. 
E)  has covalent disulfide bonds to stabilize the structure. 
A)  primary component in hair, claws, fingernails, and horns of animals. 
B)  consists of four helical strands arranged as twisted pairs of two-stranded coiled coils. 
C)  has associated hydrophobic strips on the two coiled coils. 
D)  presence of properly placed polar amino acids help to solubilize α-keratin. 
E)  has covalent disulfide bonds to stabilize the structure.

Question 13

Which of the following proteins does not have quaternary structure?

Accepted Answer

A)  immunoglobulins 
B)  insulin 
C)  glycogen phosphorylase 
D)  myoglobin 
E)  alcohol dehydrogenase 
A)  immunoglobulins 
B)  insulin 
C)  glycogen phosphorylase 
D)  myoglobin 
E)  alcohol dehydrogenase

Question 14

Electrostatic interactions among amino acid residues on proteins may be damped out by high concentrations of:

Accepted Answer

A)  water. 
B)  organic solvents. 
C)  salts. 
D)  heat. 
E)  all of the above. 
A)  water. 
B)  organic solvents. 
C)  salts. 
D)  heat. 
E)  all of the above.

Question 15

All are classes of globular proteins according to type and arrangement of secondary structure EXCEPT:

Accepted Answer

A)  small metal- and disulfide-rich proteins. 
B)  parallel or mixed β-sheet. 
C)  antiparallel β-sheet. 
D)  antiparallel α-helix. 
E)  all are true. 
A)  small metal- and disulfide-rich proteins. 
B)  parallel or mixed β-sheet. 
C)  antiparallel β-sheet. 
D)  antiparallel α-helix. 
E)  all are true.

Question 16

Which of the following items was one of the crucial elements of the Anfinsen experiment with ribonuclease A?

Accepted Answer

A)  hydrophobic interactions were disrupted by the addition of β-mercaptoethanol 
B)  correct formation of disulfide bonds was achieved even with urea present 
C)  removal of β-mercaptoethanol resulted in complete denaturation of the protein 
D)  the presence of 8 cysteine residues means that there are 105 different disulfide bond possibilities 
E)  none of the above 
A)  hydrophobic interactions were disrupted by the addition of β-mercaptoethanol 
B)  correct formation of disulfide bonds was achieved even with urea present 
C)  removal of β-mercaptoethanol resulted in complete denaturation of the protein 
D)  the presence of 8 cysteine residues means that there are 105 different disulfide bond possibilities 
E)  none of the above

Question 17

When the peptide (AEFFLAMEP) forms an α-helix, which amino acid residue would be closest to being in the same position on the same face of the helix as is the initial alanine residue?

Accepted Answer

A)  F(3) 
B)  A(6) 
C)  E(8) 
D)  P(9) 
E)  L(5) 
A)  F(3) 
B)  A(6) 
C)  E(8) 
D)  P(9) 
E)  L(5)

Question 18

Tertiary structure of proteins depends on all of the following EXCEPT:

Accepted Answer

A)  protein structure depends on primary structure. 
B)  α-helices and β-sheets often associate and pack close together. 
C)  secondary structures form whenever possible. 
D)  proteins are stable as a single-layer structure. 
E)  peptide segments between secondary structures are short. 
A)  protein structure depends on primary structure. 
B)  α-helices and β-sheets often associate and pack close together. 
C)  secondary structures form whenever possible. 
D)  proteins are stable as a single-layer structure. 
E)  peptide segments between secondary structures are short.

Question 19

____ β-sheets characteristically distribute hydrophobic side chains on both sides of the sheet, and ____ β-sheets are usually arranged with all their hydrophobic residues on one side of the sheet.

Accepted Answer

A)  Antiparallel, parallel 
B)  Antiparallel, antiparallel 
C)  Parallel, antiparallel 
D)  Parallel, parallel 
E)  None of the above 
A)  Antiparallel, parallel 
B)  Antiparallel, antiparallel 
C)  Parallel, antiparallel 
D)  Parallel, parallel 
E)  None of the above

Question 20

____ and ____ act as helix breakers due to their unique structure, which fixes the value of the Cα−N−C bond angle.

Accepted Answer

A)  Histidine, lysine 
B)  Proline, hydroxyproline 
C)  Arginine, lysine 
D)  Serine, threonine 
E)  Tyrosine, serine 
A)  Histidine, lysine 
B)  Proline, hydroxyproline 
C)  Arginine, lysine 
D)  Serine, threonine 
E)  Tyrosine, serine

Exam 6: Proteins: Secondary, Tertiary, and Quaternary Structure

Silk fibers consist of ____ proteins consisting of alternating ____ and ____ or ____ residues.

Secondary and higher orders of structure are determined by all EXCEPT:

____ is an example of a disulfide-rich protein.

Which of the following amino acids would generally not be found in an α-helix?

Amino acid side chains capable of forming hydrogen bonds are usually located on the protein ____ and form hydrogen bonds primarily with the ____.

The "permanent" part of adding wave in hair is primarily due to:

Prolyl hydroxylase has all of the following characteristics EXCEPT:

In hemoglobin, a ____ protein, the space between the helices is filled efficiently and tightly with mostly ____ amino acid chains and with ____ side chains facing the outside of the protein structure.

All of the information necessary for folding the peptide chain into its "native" structure is contained in the ____ of the peptide.

Polylysine is a random coil when the pH is less than 11, while it forms an α-helix if the pH is raised to greater than 12. This is because at pH 12:

The unique composition of collagen is accommodated in a structure called a(n):

α-Keratin has all of the following characteristics EXCEPT:

Which of the following proteins does not have quaternary structure?

Electrostatic interactions among amino acid residues on proteins may be damped out by high concentrations of:

All are classes of globular proteins according to type and arrangement of secondary structure EXCEPT:

Which of the following items was one of the crucial elements of the Anfinsen experiment with ribonuclease A?

When the peptide (AEFFLAMEP) forms an α-helix, which amino acid residue would be closest to being in the same position on the same face of the helix as is the initial alanine residue?

Tertiary structure of proteins depends on all of the following EXCEPT:

____ β-sheets characteristically distribute hydrophobic side chains on both sides of the sheet, and ____ β-sheets are usually arranged with all their hydrophobic residues on one side of the sheet.

____ and ____ act as helix breakers due to their unique structure, which fixes the value of the Cα−N−C bond angle.

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

Silk fibers consist of proteins consisting of alternating and or residues.

Amino acid side chains capable of forming hydrogen bonds are usually located on the protein and form hydrogen bonds primarily with the .

In hemoglobin, a protein, the space between the helices is filled efficiently and tightly with mostly amino acid chains and with side chains facing the outside of the protein structure.

β-sheets characteristically distribute hydrophobic side chains on both sides of the sheet, and β-sheets are usually arranged with all their hydrophobic residues on one side of the sheet.

and act as helix breakers due to their unique structure, which fixes the value of the C_α−N−C bond angle.