The primary structure of a protein is known and the location of internal disulfide bonds has been determined. How could one predict whether there might be secondary structures in my protein once it folds into a native conformation?

Perform a Ramachandran plot/analysis on my protein

Perform X-ray diffraction on my protein

Run two-dimensional gel electrophoresis on my protein

Determine if there is more than one polypeptide in the protein

Identify specific motifs in the primary structure

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

Fold proteins into a native conformation

Assemble protein subunits into a quaternary structure

Transport proteins to either the plasma membrane or release them from cells to the extracellular space

Add cofactors, coenzymes or prosthetic groups to proteins as they are synthesized

Move proteins from endoplasmic reticulum to the Golgi apparatus

Protein folding to a native conformation is highly dependent upon all of the following, except:

the rotation about the peptide bond.

rotation about the alpha-carbon, carbon bond in the backbone.

the polar character of sequences of amino acids.

the relative size of amino acid R-groups.

the rotation about the alpha-carbon, nitrogen bond.

Certain amino acids destabilize or prevent formation of alpha-helices. Which amino acid is more likely to be found in these structures based on its charge and R- group size?

A sequence of several Glutamate

Which is the more stable beta-sheet: parallel or antiparallel?

Antiparallel, due to more linear H-bonds and a high concentration of Ala and Gly

Parallel, due to alignment of all terminal amino- groups on one side and all carboxyl-groups on the other side

Parallel, due to a high concentration of proline residues, promoting more linear H-bonds

Antiparallel, due to a more elongated structure than parallel sheets

Antiparallel, because beta-turns can join the strands, an arrangement which is not possible with parallel sheets

Collagen and alpha-keratin share which structural feature that promotes stability?

A right-handed coil, which is much more stable than a left-handed coil due to hydrogen bonding

A high concentration of Gly residues, which permits close association of polypeptides in coils

A left-handed coil, which is much more compact than a right-handed coil

A high concentration of polar amino acids that can form hydrogen bonds

I would like structural information on a newly described cytosolic protein. It is 18,000 daltons and contains a number of phosphoryl groups. What method should I use?

Nuclear magnetic resonance because the protein is small and has a lot of phosphate

X-ray diffraction because small proteins are easiest to crystallize

Mass spectroscopy, which is best for highly charged proteins

Two-dimensional gel electrophoresis, which can yield new information about this protein

Nuclear magnetic resonance because the resolution is superior to other structural methods

In most cases, protein folding is complex and inhibited by aggregation. Which of the following is false regarding protein folding?

All proteins require the input of energy and the assistance of chaperones for folding.

As ΔS decreases, ΔG increases.

Chaperones of the heat shock classes do not promote folding, but rather inhibit aggregation.

Enzymes promote the formation of proper disulfide linkages by eliminating improper folding.

Secondary structures usually form first in folding.

Which of the following is true of the binding energy derived from enzyme-substrate interactions?

It is sometimes used to hold two substrates in the optimal orientation for reaction.

It cannot provide enough energy to explain the large rate accelerations brought about by enzymes.

It is the result of covalent bonds formed between enzyme and substrate.

Most of it is derived from covalent bonds between enzyme and substrate.

Most of it is used up simply binding the substrate to the enzyme.

The concept of "induced fit" refers to the fact that:

substrate binding may induce a conformational change in the enzyme, which then brings catalytic groups into proper orientation.

enzyme specificity is induced by enzyme-substrate binding.

enzyme-substrate binding induces an increase in the reaction entropy, thereby catalyzing the reaction.

enzyme-substrate binding induces movement along the reaction coordinate to the transition state.

when a substrate binds to an enzyme, the enzyme induces a loss of water (desolvation) from the substrate.

The benefit of measuring the initial rate of a reaction V0 is that at the beginning of a reaction:

changes in [S] are negligible, so [S] can be treated as a constant.

[ES] can be measured accurately.

changes in Km are negligible, so Km can be treated as a constant.

varying [S] has no effect on V0.

The role of the metal ion (Mg2+) in catalysis by enolase is to:

facilitate general base catalysis.

act as a general acid catalyst.

act as a general base catalyst.

facilitate general acid catalysis.

stabilize protein conformation.

A good transition-state analog:

binds to the enzyme more tightly than the substrate.

binds covalently to the enzyme.

binds very weakly to the enzyme.

must be almost identical to the substrate.

Enzyme X exhibits maximum activity at pH = 6.9. X shows a fairly sharp decrease in its activity when the pH goes much lower than 6.4. One likely interpretation of this pH activity is that:

a His residue on the enzyme is involved in the reaction.

a Glu residue on the enzyme is involved in the reaction.

the enzyme has a metallic cofactor.

the enzyme is found in gastric secretions.

the reaction relies on specific acid-base catalysis.

In competitive inhibition, an inhibitor:

binds reversibly at the active site.

binds at several different sites on an enzyme.

binds covalently to the enzyme.

lowers the characteristic Vmax of the enzyme.

The Lineweaver-Burk plot is used to:

solve, graphically, for the rate of an enzymatic reaction at infinite substrate concentration.

determine the equilibrium constant for an enzymatic reaction.

extrapolate for the value of reaction rate at infinite enzyme concentration.

illustrate the effect of temperature on an enzymatic reaction.

solve, graphically, for the ratio of products to reactants for any starting substrate concentration.

Which of the following statements concerning protein domains is true?

They may retain their correct shape even when separated from the rest of the protein.

They are a form of secondary structure.

They are examples of structural motifs.

They consist of separate polypeptide chains (subunits).

They have been found only in prokaryotic proteins.

An alpha helix would be destabilized most by:

interactions between neighboring Asp and Arg residues.

an electric dipole spanning several peptide bonds throughout the α helix.

interactions between two adjacent hydrophobic Val residues.

the presence of an Arg residue near the carboxyl terminus of the α helix.

the presence of two Lys residues near the amino terminus of the α helix.

Which of the following should be considered when looking for a way to increase an enzyme reaction rate?

Decreasing Kd between the substrate and enzyme

Which of the following could not be part of a reversible enzyme inhibition mechanism?

An enzyme that performs metal ion catalysis

The release of a prosthetic group

Protonation of amino acid side chains by a slight change in pH

Binding of a small molecule to the active site using hydrogen bonds

To further understand glycolysis kinetics, one of the enzymes studied in the presence of an allosteric effector (+) and absence (-). All of the following statements about the allosteric effector are false EXCEPT:

The effector binds noncovalently at the active site.

The effector binds covalently at the active site.

The release of a proton accompanies binding of the effector.

The release of a proton accompanies release of the effector.

The effector causes a slight change in pH.

The effector increased both Km and Vmax and thus it is said to be an allosteric activator.

Km decreased but Vmax increased, making the effector an allosteric activator.

Both Km and Vmax decreased, making the effector an allosteric inhibitor.

Km increased but Vmax decreased, making the effector an allosteric inhibitor.

Enzymes catalyze biochemical reactions by altering which of the following quantities associated with the reaction?

The change in Gibb's free energy ΔG'0

Which of the following molecules cannot be classified as an enzymatic cofactor?

Flavin adenine dinucleotide (FAD)

In order to analyze the catalytic effect of two different enzymes on the same chemical reaction, it is best to compare which of the following quantities?

The differences in free energy between the reactants and products

The differences in enthalpy between the reactants and products

The differences in entropy between the reactants and products

The active site model (also called the lock and key model) of enzyme-substrate binding differs from the induced fit model in which of the following ways?

The induced fit model holds that enzyme-substrate binding does not take place at the enzyme's active site

The induced fit model holds that the shape of the substrate is irrelevant to enzyme-substrate binding

The induced fit model holds that the shape of the active site is permanently altered by substrate binding

Local conditions can affect the specificity of an enzyme for its substrate, and thus the enzyme's catalytic ability: which of the following alterations would most likely not affect an enzyme in this manner?

Increased substrate concentration

Given that ΔG°' for the reaction S⇌P is negative in the direction of S→P, reaction equilibrium favors the formation of which substance?

The reaction does not proceed in either direction

The reaction proceeds equally in both directions

How would the addition of a catalyst to the reaction S⇌P affect the difference between the free energies of S and P in their ground states (ΔG°')?

The change in ΔG°' cannot be predicted without more information

ΔG°' would become less negative

ΔG°' would become more negative

Protein Structure and Function Quiz

Quiz

•

Biology

•

University

•

Practice Problem

•

Hard

John Watts

Used 4+ times

FREE Resource

47 questions

Show all answers

1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which type of weak interaction is most important for cohesiveness and strength between beta-strands in beta-sheets?

Ionic

Hydrophobic

Covalent

Hydrogen bonds

van der Waal's interactions

2.

FILL IN THE BLANK QUESTION

30 sec • 1 pt

Which amino acid would most likely be found in the interior of a globular protein?

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

How many of the 20 common amino acids have rings in their structures?

2

3

4

5

6

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the highest level of protein structure in human insulin, which has two polypeptides of different mass linked by several disulfide bonds?

Primary

Secondary

Tertiary

Quaternary

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What specific functional group is used to form disulfide bonds?

Carboxyl

Carbonyl

Sulfhydryl

Phosphoryl

Guanidino

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which term refers to molecules like proteins, which can have both polar and nonpolar regions?

Amphipathic

Amphigenic

Amphibolic

Amphiphatic

Amphoteric

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Given that all 20 common amino acids have at least two oppositely charged, ionizable R-groups, which statement below is incorrect?

Solutions of amino acids can act as buffers.

All amino acids are zwitterions.

All amino acids carry at least one charge across the full range of their titration curves.

Amino acid isoelectric points should be near neutrality.

It is not possible to fully deprotonate amino acids.

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Protein Structure and Function Quiz

47 questions

Which type of weak interaction is most important for cohesiveness and strength between beta-strands in beta-sheets?

Which amino acid would most likely be found in the interior of a globular protein?

How many of the 20 common amino acids have rings in their structures?

What is the highest level of protein structure in human insulin, which has two polypeptides of different mass linked by several disulfide bonds?

What specific functional group is used to form disulfide bonds?

Which term refers to molecules like proteins, which can have both polar and nonpolar regions?

Given that all 20 common amino acids have at least two oppositely charged, ionizable R-groups, which statement below is incorrect?

If a protein is denatured, what is lost?

The primary structure of a protein is known and the location of internal disulfide bonds has been determined. How could one predict whether there might be secondary structures in my protein once it folds into a native conformation?

What important function do molecular chaperones perform?

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