Biochem

Ramachandran plots measure which dihedral angles? A. φ (phi) and ψ (psi) angles B. ψ (psi) and ω (omega) angles C. φ (phi) and ω (omega) angles D. φ (phi), ψ (psi), and ω (omega) angles

A. φ (phi) and ψ (psi) angles

Which protein would elute first from a gel filtration column? A. protein A, with Mr = 27,000 B. protein B, with Mr = 58,400 C. protein C, a homodimer with protomer Mr = 11,300 D. protein D, with Mr = 15,600

B. protein B, with Mr = 58,400

Would the mutation have a greater or lesser impact on stability at pH 10.0pH 10.0 compared to pH 3.0? lesser, because a greater fraction of Lys can remain buried in the core at pH 10.0 greater, because high pH values destabilize proteins lesser, because a less acidic environment contributes to general protein stability no change, because the Lys side chain p𝐾a is above 10.0 so the side chain remains charged

lesser, because a greater fraction of Lys can remain buried in the core at pH 10.0

Choose two amino acids that would be reasonable candidates for the pocket-Val 6 interaction. leucine glutamate phenylalanine arginine lysine

leucine phenylalanine

Weak acid

partially dissociates into ions, acetic acid, larger pKa

In what area of the titration curve for carbonic acid (H2CO3) is the molecule fully deprotonated? A. the far left B. the far right C. at the center, at the pKa D. in the area about 1 pH unit higher than the pKa

B. the far right

Which item is the predominant factor in protein stability? A. disulfide bonds B. the hydrophobic effect C. salt bridges D. nonpeptide covalent bonds

B. the hydrophobic effect

Which aqueous solution has the lowest pH? 0.1 M0.1 M lactic acid (p𝐾a=7.86)pKa=7.86) 0.1 M0.1 M hydrofluoric acid (p𝐾a=3.20)(pKa=3.20) 0.1 M0.1 M formic acid (p𝐾a=3.75)(pKa=3.75) 0.1 M0.1 M acetic acid (p𝐾a=4.86)

0.1 M0.1 M hydrofluoric acid (p𝐾a=3.20)

Which of these situations would produce a Hill plot with a Hill coefficient less than 1? A purified protein has multiple binding sites, and ligand binding to one site decreases the affinity of other sites for the ligand. A purified protein is a single polypeptide with one ligand‑binding site, but the sample is contaminated with some partially denatured protein molecules. A purified protein is a single polypeptide with two ligand‑binding sites, each having a different affinity for the ligand. A purified protein has multiple binding sites, and ligands bind to each site independently without affecting the binding affinity of other sites.

A purified protein has multiple binding sites, and ligand binding to one site decreases the affinity of other sites for the ligand. A purified protein is a single polypeptide with one ligand‑binding site, but the sample is contaminated with some partially denatured protein molecules. A purified protein is a single polypeptide with two ligand‑binding sites, each having a different affinity for the ligand.

Which of these situations would produce a Hill plot with a Hill coefficient less than 1? A purified protein is a single polypeptide with one ligand‑binding site, but the sample is contaminated with some partially denatured protein molecules. A purified protein has multiple binding sites, and ligands bind to each site independently without affecting the binding affinity of other sites. A purified protein is a single polypeptide with two ligand‑binding sites, each having a different affinity for the ligand. A purified protein has multiple binding sites, and ligand binding to one site decreases the affinity of other sites for the ligand.

A purified protein is a single polypeptide with one ligand‑binding site, but the sample is contaminated with some partially denatured protein molecules. A purified protein is a single polypeptide with two ligand‑binding sites, each having a different affinity for the ligand. A purified protein has multiple binding sites, and ligand binding to one site decreases the affinity of other sites for the ligand.

Which amino acid would MOST likely be found in the interior of a globular protein? A. Ala B. D C. glutamate D. cysteine E. Lys

A. Ala

Which statement about protein folding is false? A. It requires protein disulfide and peptide prolyl cis-trans isomerases. B. It is a stepwise process. C. It is sometimes assisted by proteins known as chaperones. D. It is driven by changes in free energy.

A. It requires protein disulfide and peptide prolyl cis-trans isomerases.

Which statement is correct about proteins? A. Proteins can consist of more than one polypeptide chain. B. Proteins consist solely of polymerized amino acids. C. Proteins all have similar amino acid compositions. D. Proteins can, by definition, consist of no more than 2,000 amino acid residues. E. Proteins do not have ionizable groups.

A. Proteins can consist of more than one polypeptide chain.

Which statement about buffers is false? A. They have maximum buffering capacity. B. They are weak acids and bases. C. [A-] = [HA] when pH = pKa D. They can sometimes be biological macromolecules.

A. They have maximum buffering capacity.

Which statement about hydrogen bonds is false? A. They only occur between water molecules. B. They are weak compared with covalent bonds. C. They cause acid-base reactions in aqueous solutions to be very rapid. D. They have an optimal geometry.

A. They only occur between water molecules.

he amino acid sequences of proteins: A. can be used to establish evolutionary relationships between organisms. B. are an example of tertiary structure. C. are similar within a given organism. D. are also referred to as "consensus sequences."

A. can be used to establish evolutionary relationships between organisms.

α-Keratin proteins constitute almost the entire dry weight of horns and hooves in mammals. The strength of α-keratin proteins comes from: A. cross-linking of α helices by disulfide bonds. B. a close packing of β sheets. C. a triple helix. D. high concentrations of charged amino acids.

A. cross-linking of α helices by disulfide bonds.

Collagen: A. has fibrils consisting of cross-linked triple helices of polypeptide chains. B. dose not have quaternary structure. C. consists of -helical subunits. D. has a primary structure of repeating -Glu-X-Y-.

A. has fibrils consisting of cross-linked triple helices of polypeptide chains.

Weak acids: A. only partially ionize in water. B. have a pKa < 7. C. react very slowly with bases .D. are formed by dilution of strong acids.

A. only partially ionize in water.

Which statement is false? A. protein structure is commonly defined at four levels. between organisms. B. The function of a protein is a result of its amino acid sequence. C. Orthologs are homologs found in the same species. D. It is possible to change the amino acid sequence of a protein and have no effect on its function.

A. protein structure is commonly defined at four levels. between organisms.

Denaturing gel electrophoresis separates proteins based on differences in: A. size and shape. B. molecular mass. C. charge. D. amino acid content.

A. size and shape.

Which characteristic of protein is NOT associated with proteostasis? A. structure B. synthesis C. refolding D. degradation

A. structure

What is the actual function of a buffer system such as acetate/acetic acid? A. to maintain a constant pH in the event that the concentration of an acid or base increases B. to maintain the solution at the pKa C. to ensure that the solution has no free H+ or OH- within a specific range D. to keep the solution within one pH unit of the pKa

A. to maintain a constant pH in the event that the concentration of an acid or base increases

Based on your knowledge of the catalytic cycle of myosin in muscle contraction, why does rigor mortis occur following ATP depletion after death in vertebrates? ATP depletion following death decreases cytosolic Ca2+. ATP is required for myosin to bind to actin. ATP is required for actin polymerization. ATP is required to dissociate myosin from actin.

ATP is required to dissociate myosin from actin.

Based on your knowledge of the catalytic cycle of myosin in muscle contraction, why does rigor mortis occur following ATP depletion after death in vertebrates? ATP is required to dissociate myosin from actin. ATP depletion following death decreases cytosolic Ca2+. ATP is required for actin polymerization. ATP is required for myosin to bind to actin.

ATP is required to dissociate myosin from actin.

Why might a single drug be effective in treating these two different conditions? Amyloid fibrils also develop in the pancreas in association with type 2 diabetes. The fibril‑forming amyloid protein expressed in the brain is also expressed in the pancreas. A deficiency in aromatic amino acids causes β cell dysfunction in patients with type 2 diabetes. Amyloid fibrils formed in the brain travel to the pancreas, which causes β cell dysfunction.

Amyloid fibrils also develop in the pancreas in association with type 2 diabetes.

Why might a single drug be effective in treating these two different conditions? The fibril‑forming amyloid protein expressed in the brain is also expressed in the pancreas. Amyloid fibrils formed in the brain travel to the pancreas, which causes β cell dysfunction. A deficiency in aromatic amino acids causes β cell dysfunction in patients with type 2 diabetes. Amyloid fibrils also develop in the pancreas in association with type 2 diabetes.

Amyloid fibrils also develop in the pancreas in association with type 2 diabetes.

Why does the Asp-His ion pair contribute more energy at pH 6.0pH 6.0 than at low or high pH? At pH 2.0,pH 2.0, Asp and His are both deprotonated. At pH 6.0,pH 6.0, Asp is deprotonated and His may be protonated. At pH 6.0,pH 6.0, Asp is protonated and His may be deprotonated. At pH 10.0,pH 10.0, Asp and His are both protonated. At pH 10.0,pH 10.0, Asp is protonated and His may be deprotonated.

At pH 6.0,pH 6.0, Asp is deprotonated and His may be protonated.

The specific activity of a protein in crude cellular extract is 15 units/mg. Following a purification process, involving precipitation with ammonium sulfate and multiple chromatography steps, the specific activity of the protein is 12,000 units/mg. What is the purification factor? A. 180,000 B. 800 C. 0.00125 D. 15 E. 12,000

B. 800

Weak noncovalent interactions: A. always involve water. B. can have a large cumulative effect. C. do not include ionic interactions. D. combine to form covalent interactions.

B. can have a large cumulative effect.

Denaturing followed by renaturing of a protein: A. always results in the protein regaining its function. B. demonstrates that primary structure dictates tertiary structure. C. requires heat. D. requires breaking and reforming disulfide bonds.

B. demonstrates that primary structure dictates tertiary structure.

What important function do molecular chaperones perform? A. assemble protein subunits into a quaternary structure B. fold proteins into a native conformation C. transport proteins to either the plasma membrane or release them from cells to the extracellular space D. add cofactors, coenzymes, or prosthetic groups to proteins as they are synthesized E. move proteins from endoplasmic reticulum to the Golgi apparatus

B. fold proteins into a native conformation

An unusual characteristic of H2O is: A. greater density in solid form (ice) than in liquid form (water). B. high heat of vaporization. C. low specific heat. D. not readily forming intermolecular interactions.

B. high heat of vaporization.

When H2O ionizes: A. the ∆G° = 0 kJ/mol. B. it has a measurable Keq. C. its concentration (7 M) does not appreciably change. D. free H+ ions are present in solution.

B. it has a measurable Keq.

Given that an helix has 3.6 amino acids per turn and and a rise of 5.4 Å per turn, what is the length per amino acid of the helix? A. 3.6 Å B. 5.4 Å C. 1.5 Å D. 19.4 Å

C. 1.5 Å

Trypsin catalyzes the hydrolysis of peptide bonds in which a Lys or Arg residue contributes a carbonyl group LL-37, an antimicrobial peptide with 37 residues has 6 Lys residues and 5 Arg residues. How many smaller peptides will LL-37 yield upon trypsin cleavage? A. 6 B. 5 C. 12 D. 37 E. 11

C. 12

What is the highest level of protein structure in human insulin, which has two polypeptides of different mass linked by several disulfide bonds? A. primary B. secondary C. tertiary D. quaternary

D. quaternary

Which component is absolutely necessary for the purification of a protein? A. column chromatography B. the gene sequence of the protein C. a means of detecting the protein D. a centrifuge

C. a means of detecting the protein

A new protein resembling myosin was reported. Unlike myosin, it binds calcium. Its isoelectric point and molecular weight are very similar to those of myosin. Which method would BEST separate the new protein from myosin if those two proteins were in the same buffer solution? A. ion-exchange chromatography B. size-exclusion chromatography C. affinity chromatography D. dialysis E. fractionation

C. affinity chromatography

At what pH values will histidine have a net neutral charge? A. below 1.82 B. between 1.82 and 6.0 C. between 6.0 and 9.17 D. above 9.17 E. There are no pH values where histidine will have a net neutral charge.

C. between 6.0 and 9.17

Which atom does NOT commonly form hydrogen bonds between or within biological molecules? A. oxygen B. hydrogen C. carbon D. nitrogen

C. carbon

Which feature is NOT associated with globular proteins? A. domains B. motifs C. classified as either all α or all β D. intrinsically disordered regions of structure

C. classified as either all α or all β

Dissolving table sugar into iced tea is an energetically favorable reaction due to a(n): A. increase in enthalpy as heat moves into the sugar. B. decrease in free energy due to broken weak interactions between sugar molecules. C. increase in entropy as the sugar dissolves. D. increase in free energy because there is no longer a solvation layer around the sugar crystal.

C. increase in entropy as the sugar dissolves.

The hydrophobic effect: A. only occurs with amphipathic molecules. B. does not occur in biological membranes. C. is driven by an increase in entropy of water molecules. D. results from attractive forces between hydrophobic molecules.

C. is driven by an increase in entropy of water molecules.

What measurement increases during purification of an enzyme? A. activity B. total protein C. specific activity D. fraction volume

C. specific activity

Quaternary structure: A. describes how oligomers are assembled into protomers. B. refers to proteins with identical subunits. C. refers to proteins with four subunits. D. refers to an arrangement of tertiary protein subunits in a three-dimensional complex.

D. refers to an arrangement of tertiary protein subunits in a three-dimensional complex.

Conjugate base of CH3COOH

CH3COO-

Conjugate base of CH3NH3+

CH3NH2

What is the concentration of H+ in a solution of 0.01 M NaOH? Because NaOH is a strong base, it dissociates completely into Na+ and OH-. A. 0.01 M B. 10^-13 M C. 10^-14 M D. 10^-12 M

D. 10^-12 M

What is the pH of a 0.1 mM solution of hydrochloric acid at 37 °C? A. 0.1 B. 1 C. 3 D. 4

D. 4

The pKa of a weak acid: A. is a function of its concentration. B. is the pH at which it has no net charge. C. is <0 at pH > 7. D. can be determined from its titration curve.

D. can be determined from its titration curve.

Nonpolar compounds: A. force surrounding H2O molecules to become disordered. B. increase entropy (∆S) when dissolved in water. C. decrease enthalpy (∆H) when dissolved in water. D. interfere with the hydrogen bonding among H2O molecules.

D. interfere with the hydrogen bonding among H2O molecules.

The pH of an aqueous solution: A. must remain at 7. B. is not affected by added OH-. C. depends solely on the ionization of water. D. is a function of hydrogen ion concentration (to a reasonable approximation).

D. is a function of hydrogen ion concentration (to a reasonable approximation).

The sheet: A. can be either parallel or perpendicular. B. has strands in which the R groups of the amino acids are all on the same side of the sheet. C. is composed of amino acid residues all very near each other in the primary structure. D. is primarily stabilized by hydrogen bonds.

D. is primarily stabilized by hydrogen bonds.

Circular dichroism can NOT: A. provide a rough estimate for the fraction of the protein made up of the two common secondary structures. B. monitor the denaturation of a protein. C. monitor conformational changes in a protein. D. obtain a high-resolution three-dimensional structure.

D. obtain a high-resolution three-dimensional structure.

Select the true statements about denaturation. A denatured protein has a different primary structure than its native state. A competitive enzyme inhibitor acts by denaturing the enzyme. Denaturation of an enzyme will cause a loss of its catalytic activity. A denatured protein has a different tertiary structure than its native state. Egg white meringue contains denatured egg white proteins. Denaturation and digestion refer to the same process.

Denaturation of an enzyme will cause a loss of its catalytic activity. A denatured protein has a different tertiary structure than its native state. Egg white meringue contains denatured egg white proteins.

Which amino acid would destabilize an amphipathic α helix if placed in the middle of one? A. glycine B. proline C. glutamate D. valine E. All of these amino acids would potentially destabilize an amphipathic α helix.

E. All of these amino acids would potentially destabilize an amphipathic α helix

A motif in the glycolysis enzyme hexokinase could NOT contain: A. a β turn. B. a β sheet. C. an helix. D. disulfide bonds E. All of these could be found in a motif.

E. All of these could be found in a motif.

Given that all 20 common amino acids have at least two oppositely charged groups, which statement is NOT correct? A. Solutions of amino acids can act as buffers. B. All amino acids are zwitterions. C. All amino acids carry at least one charge across the full range of their titration curves. D. Amino acid isoelectric points should be near neutrality. E. It is not possible to fully deprotonate amino acids.

E. It is not possible to fully deprotonate amino acids

Why is there very little allowable rotation around the peptide bond? A. Peptide bonds are amide bonds. B. The R group prevents rotation about the peptide bond, except in glycine. C. The C—N bond is shorter. D. Peptide bonds are only formed in the cis configuration. E. The partial double-bond character makes the peptide bond planar.

E. The partial double-bond character makes the peptide bond planar.

Conjugate base of H3Po4

H2PO4-

Ethane (CH3CH3)(CH3CH3) and ethanol (CH3CH2OH)(CH3CH2OH) differ in their molecular makeup by only one atom, yet ethanol is much more soluble in water than ethane. Select the features of ethanol that make it more water soluble than ethane.

Ethanol is polar and Ethanol participates in hydrogen bonding

How would you expect H2S to compare with H2O in terms of boiling point and solvent polarity? H2S has a higher boiling and is a more polar solvent than H2O.H2O. H2S has a lower boiling and is a less polar solvent than H2O.H2O. H2S has a higher boiling and is a less polar solvent than H2O.H2O. H2S has a lower boiling and is a more polar solvent than H2O.

H2S has a lower boiling and is a less polar solvent than H2O.

How would you expect H2SH2S to behave in terms of hydrogen bonding? H2SH2S forms hydrogen bonds with H2O,H2O, but not with itself. H2SH2S forms hydrogen bonds with itself and with H2O.H2O. H2SH2S does not form hydrogen bonds with itself or with H2O.H2O. H2SH2S forms hydrogen bonds with itself, but not with H2O.

H2SH2S forms hydrogen bonds with H2O,H2O, but not with itself.

Conjugate base of H2CO3

HCO3-

Which of the IgG molecules specifically binds one of the ligands? IgG2 IgG1

IgG1

How would the Met to Lys mutation affect the thermal denaturation of lysozyme at pH 3.0?pH 3.0? It will not change the 𝑇m at pH 3.0 because the Lys side chain p𝐾a is 10.53. It will stabilize the protein and raise the 𝑇m, shifting the curve to higher temperatures. It will destabilize the protein and lower the 𝑇m, shifting the curve to the left. It will not affect stability, but it will decrease the 𝑇m and shift the curve to lower temperatures.

It will destabilize the protein and lower the 𝑇m, shifting the curve to the left.

Why can protein structures be more highly conserved than individual amino acid sequences? The amino acid sequence of a protein is not related to the structure of the protein. Dysfunctional proteins primarily arise from changes to amino acid sequence, not changes to protein structure. Many different amino acid sequences can give rise to similar protein structures. Changes to protein structure occur independently of changes to the amino acid sequence.

Many different amino acid sequences can give rise to similar protein structures.

Why would molecules with aromatic substituents disrupt the formation of amyloid? Molecules with aromatic substituents interfere with stacking of aromatic residues within fibrils. Molecules with aromatic substituents prevent α helix formation in amyloid fibrils. Molecules with aromatic substituents cause highly unordered fibrils to become more structured. Molecules with aromatic substituents prevent β sheet formation in amyloid fibrils.

Molecules with aromatic substituents interfere with stacking of aromatic residues within fibrils.

Why would molecules with aromatic substituents disrupt the formation of amyloid? Molecules with aromatic substituents prevent β sheet formation in amyloid fibrils. Molecules with aromatic substituents cause highly unordered fibrils to become more structured. Molecules with aromatic substituents prevent α helix formation in amyloid fibrils. Molecules with aromatic substituents interfere with stacking of aromatic residues within fibrils.

Molecules with aromatic substituents interfere with stacking of aromatic residues within fibrils.

How do mutations that affect the viral protein coat allow human immunodeficiency virus (HIV) to evade the immune system? Changes to the viral protein coat enable the bound virus to leave the antigen‑binding site. Mutant viral coat proteins attract macrophages to the pathogen. Mutations can alter the antigenic determinant on the protein coat. The virus alters the viral protein coat to mimic host cells.

Mutations can alter the antigenic determinant on the protein coat.

Which protein has greater affinity for ligand X? Why? Protein B has greater affinity because it has a lower 𝐾a than Protein A. Protein B has greater affinity because it has a lower 𝐾d than Protein A. Protein A has greater affinity because it has a greater 𝐾a than Protein B. Protein A has greater affinity because it has a greater 𝐾d than Protein B.

Protein B has greater affinity because it has a lower 𝐾d than Protein A.

Which protein has greater affinity for ligand X? Why? Protein B has greater affinity because it has a lower 𝐾d than Protein A. Protein B has greater affinity because it has a lower 𝐾a than Protein A. Protein A has greater affinity because it has a greater 𝐾a than Protein B. Protein A has greater affinity because it has a greater 𝐾d than Protein B.

Protein B has greater affinity because it has a lower 𝐾d than Protein A.

What other analytic technique could you employ to determine whether the polypeptide chains in this protein are similar or different? native polyacrylamide gel electrophoresis SDS polyacrylamide gel electrophoresis polymerase chain reaction (PCR) northern blot

SDS polyacrylamide gel electrophoresis

What do the observations of Pauling and Corey tell us about the ease of rotation about the C−N peptide bond? The C−N peptide bond is important to protein structure and has limited rotation giving rise to the ψ angle. The C−N peptide bond can rotate easily, providing flexibility to a protein structure. The C−N peptide bond does not rotate. The C−N peptide bond is important to protein structure and has limited rotation giving rise to the ϕ angle.

The C−N peptide bond does not rotate.

What does the length of the C−N bond in the peptide linkage indicate about its strength (i.e., whether it is single, double, or triple)? The C−N peptide bond is stronger than a C=N bond. The C−N peptide bond has similar strength to a C=N bond. The C−N peptide bond is stronger than a C−N single bond. The C−N peptide bond has similar strength to a C−NC single bond.

The C−N peptide bond is stronger than a C−N single bond.

What do you predict about the average duration of H bonds at the high temperature in comparison to the low temperature? The average bond duration decreases, then increases. The average bond duration increases. The average bond duration decreases. There is no change in the average bond duration.

The average bond duration decreases.

Why does death occur if half the oxygen‑binding sites are still available to transport O2? The binding of CO stabilizes the T state of hemoglobin, resulting in a lower affinity for oxygen. Once hemoglobin binds CO, it can only bind additional CO molecules, not O2. The binding of CO shifts hemoglobin to the R state, resulting in a higher affinity for oxygen. The CO combines with oxygen molecules to form excessive amounts of CO2.

The binding of CO shifts hemoglobin to the R state, resulting in a higher affinity for oxygen.

What do these observations indicate about the source of the cooperativity in hemoglobin? BPG regulates the cooperative behavior of hemoglobin. Cooperativity arises from the bicarbonate buffer system. Individual subunits are capable of binding O2 cooperatively. The cooperative behavior of hemoglobin arises from subunit interactions.

The cooperative behavior of hemoglobin arises from subunit interactions.

A monoclonal antibody binds to G‑actin but not to F‑actin. What does this tell you about the epitope recognized by the antibody? An unexposed epitope within G‑actin relocates to the protein's surface when actin polymerizes. The epitope is likely to be a structure that is buried when G‑actin polymerizes to form F‑actin. There are too many epitopes present on F‑actin for the antibody to bind. The polymerization process removes the epitope, preventing the antibody from recognzing F‑actin.

The epitope is likely to be a structure that is buried when G‑actin polymerizes to form F‑actin.

How can this information help determine the number of polypeptide chains in an oligomeric protein? The weight ratio of protein to DNP‑valine equals the number of polypeptide chains. The molar ratio of DNP‑valine to protein equals the number of polypeptide chains. The molar ratio of protein to DNP‑valine equals the number of polypeptide chains. The weight ratio of DNP‑valine to protein equals the number of polypeptide chains.

The molar ratio of DNP‑valine to protein equals the number of polypeptide chains.

How does expressing a different VSG allow T. brucei to evade the immune system? The pathogen expresses a new VSG variant and evades the host antibodies against the earlier VSG variant. Random chance produces some VSG variants that bind and inactivate the antibody variable domains. The switch to a different VSG variant prevents host antigens from recognizing protozoan antibodies. Some VSG variants allow the protozoan to strongly bind host immune cells, preventing an immune response.

The pathogen expresses a new VSG variant and evades the host antibodies against the earlier VSG variant.

What is the effect on the oxygen binding capacity of these hemoglobin variants? The variants no longer form a tetramer and, therefore, are unable to bind and carry oxygen. The formation of these variants has no effect on the hemoglobin's ability to bind and carry oxygen. The variants have an increased affinity for oxygen, so oxygen binds more tightly to the heme molecule. The variants are stuck in the T state, resulting in a weaker bond between oxygen and the heme molecule.

The variants have an increased affinity for oxygen, so oxygen binds more tightly to the heme molecule.

he associations between biomolecules are often stabilized by hydrogen bonds, electrostatic interactions, hydrophobic interactions, and van der Waals interactions. How are weak interactions such as these advantageous to an organism?

They allow the reversible association of biomolecules.

Which statements correctly describe the probable locations of the amino acids? Ile and Lys are located in the interior of the protein because they are not polar. Gln is located in the interior of the protein because it is uncharged. Ala is located on the external surface of the protein because it is polar. Thr is polar and can be located on the external surface or in the interior of the protein. Asp is located on the external surface of the protein because it is charged.

Thr is polar and can be located on the external surface or in the interior of the protein. Asp is located on the external surface of the protein because it is charged.

The peptide bond is an amide linkage generated by eliminating the elements of water from the two amino acids so joined. One amino acid loses an oxygen and hydrogen atom from its ___________________ and the other amino acid loses a hydrogen atom from its _____________

a-carboxyl group and a-amino-group

Which amino acids would be expected to produce a similar sickling effect if substituted for Val at position 6? lysine alanine leucine phenylalanine arginine

alanine leucine

How do X‑ray crystallographers reconstruct the crystal structure of a protein following X‑ray diffraction? rotating the crystal with respect to the X‑ray source capturing the undiffracted X‑rays on a detector focusing the X‑rays into an image using lenses applying a Fourier transform to the reflection spots

applying a Fourier transform to the reflection spots

Which of the interactions makes the largest contribution to the stability of a folded protein? hydrogen bonding hydrophobic effect electrostatic interactions All of the interactions contribute about equally. disulfide bonds

hydrophobic effect

An increase in the concentration of 2,3‑bisphosphoglycerate (BPG) would

shift the curve to the right

An increase in the concentration of CO2 would

shift the curve to the right

An increase in the proton concentration (decrease in pH) would

shift the curve to the right

Based on this information, is more aspirin absorbed into the bloodstream from the stomach or from the small intestine and why? stomach; the pH of the stomach contents causes aspirin to be deprotonated and charged stomach; the pH of the stomach contents causes aspirin to be protonated and uncharged small intestine; the pH of the contents of the small intestine causes aspirin to be protonated and uncharged small intestine; the pH of the contents of the small intestine causes aspirin to be deprotonated and charged

stomach; the pH of the stomach contents causes aspirin to be protonated and uncharged

Strong acid

strong tendency to dissociate protons, hydrochloric acid, larger Ka

In H-NMR spectroscopy, which factor determines the shape of the spectra? the energy of a proton's β spin state the energy of a proton's α spin state the transition between a proton's α and β spin states the number of protons in the macromolecule

the transition between a proton's α and β spin states

The ATP‑binding site of an enzyme is buried in the hydrophobic interior of the enzyme. Suppose that the ionic interaction between enzyme and ATP took place at the surface of the enzyme, exposed to water. Would this enzyme-substrate interaction be stronger or weaker at the surface? Why?

weaker at the surface, because the interior of the enzyme has a lower dielectric constant than water

Which peptide segment is most likely to be part of a stable α helix at physiological pHpH ? −Gly−Gly−Gly−Ala−Gly− −Glu−Glu−Glu−Glu−Glu− −Gly−Arg−Lys−His−Gly− −Glu−Leu−Ala−Lys−Phe− −Pro−Leu−Thr−Pro−Trp− −Tyr−Trp−Phe−Val−Ile− −Lys−Lys−Ala−Arg−Ser−

−Glu−Leu−Ala−Lys−Phe−

Which observations would not likely occur in a β sheet? 𝜙=−139°;𝜓=+135°;many Val residues 𝜙=−51°;𝜓=+153°;many Gly and Pro residues 𝜙=−120°;𝜓=+120°;many Tyr residues 𝜙=+60°;𝜓=+60°;many Gly residues 𝜙=−57°;𝜓=−49°;many Ala residues

𝜙=−51°;𝜓=+153°;many Gly and Pro residues 𝜙=+60°;𝜓=+60°;many Gly residues\ 𝜙=−57°;𝜓=−49°;many Ala residues

Which observation most likely describes part of an observed α helix? 𝜙=−140°;𝜓=+130°;many Val residues 𝜙=−57°;𝜓=−47°;many Pro residues 𝜙=+60°;𝜓=+40°;many Gly residues 𝜙=−59°;𝜓=+150°;many Ser residues 𝜙=−60°;𝜓=−47°;many Ala residues

𝜙=−60°;𝜓=−47°;many Ala residues