CMR Test 1: Proteins and Enzymes with all Correct &
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Graded A+
A common reaction of two cysteine residues in proteins results in the formation of
a. thioester bonds
b. disulfide bonds
c. dithiol bonds
d. thioether bonds
e. none of the above ✔Correct Answer-b. disulfide bonds
α-Helix and β-strand are components of __________ structure
a. primary
b. secondary
c. tertiary
d. quaternary
e. all are true ✔Correct Answer-b. secondary
All of the information necessary for a protein to achieve its intricate architecture is contained within
its __________ structure.
a. primary
b. secondary
c. tertiary
d. quaternary
e. all are true ✔Correct Answer-a. primary
Amino acid side chains capable of forming hydrogen bonds are usually located on the protein
___________ and form hydrogen bonds primarily with the ___________________.
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 ✔Correct Answer-a. surface, water solvent
5 The resonance structure which forms the "amide plane" contains which atoms?
a. CαH-NH-CO-C-CαH
b. CαH-NH-CO
c. Cα-NH-CO-Cα
d. NH-CO
e. NH-CO-Cα ✔Correct Answer-a. CαH-NH-CO-C-CαH
6 In the majority of α-helixes, each peptide carbonyl is hydrogen bonded to the peptide N-H group
______ residues farther _____ the chain.
a. 2, down
b. 4, up
c. 3, down
d. 2, up
e. 4, down ✔Correct Answer-a. 2, down
, 7 The amino acid residue most likely to be found in a beta turn is:
a. glycine.
b. alanine.
c. valine.
d. glutamic acid.
e. leucine. ✔Correct Answer-a. glycine.
Tertiary structure is defined as:
a. the sequence of amino acids.
b. the folding of a single polypeptide chain in three-dimensional space.
c. hydrogen bonding interactions between adjacent amino acid residues into helical or pleated
segments.
d. the way in which separate folded monomeric protein subunits associate to form oligomeric
proteins.
e. all are true. ✔Correct Answer-b. the folding of a single polypeptide chain in three-dimensional
space.
The specific site on the enzyme where __________ binds and catalysis occurs is called the
_____________ site.
a. coenzyme; substrate
b. substrate; active
c. coenzyme; regulatory
d. regulatory; active
e. none of the above ✔Correct Answer-b. substrate; active
All are true for catalysts EXCEPT:
a. They work by lowering the energy of activation.
b. The average energy of the reaction is unchanged.
c. They combine transiently with the reactants promoting a reactive transition state condition.
d. They are regenerated after each reaction cycle.
e. All are true. ✔Correct Answer-e. All are true.
All are true for the enzyme-transition state complex EXCEPT:
a. It is designated as EX‡.
b. The enzyme stabilizes the transition-state complex more than it stabilizes the substrate complex.
c. The enzyme is "designed" to bind the transition-state structure more tightly than the substrate or
product.
d. The energy barrier between ES and EX‡ is less than the energy barrier between S and X‡.
e. All are true. ✔Correct Answer-b. The enzyme stabilizes the transition-state complex more than it
stabilizes the substrate complex.
12 Transition-state analogs are:
a. approximations of the transition state that bind more tightly than the substrate.
b. compounds that compete for the active site, but are not necessarily very similar to the substrate.
c. stable molecules that can not be expected to resemble the true transition state too closely.
d. stable chemically and structurally similar molecules to the transition state.
e. all of the above. ✔Correct Answer-d. stable chemically and structurally similar molecules to the
transition state.
13 All are characteristic of allosteric enzymes EXCEPT:
100% Verified Answers |Latest Version |Already
Graded A+
A common reaction of two cysteine residues in proteins results in the formation of
a. thioester bonds
b. disulfide bonds
c. dithiol bonds
d. thioether bonds
e. none of the above ✔Correct Answer-b. disulfide bonds
α-Helix and β-strand are components of __________ structure
a. primary
b. secondary
c. tertiary
d. quaternary
e. all are true ✔Correct Answer-b. secondary
All of the information necessary for a protein to achieve its intricate architecture is contained within
its __________ structure.
a. primary
b. secondary
c. tertiary
d. quaternary
e. all are true ✔Correct Answer-a. primary
Amino acid side chains capable of forming hydrogen bonds are usually located on the protein
___________ and form hydrogen bonds primarily with the ___________________.
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 ✔Correct Answer-a. surface, water solvent
5 The resonance structure which forms the "amide plane" contains which atoms?
a. CαH-NH-CO-C-CαH
b. CαH-NH-CO
c. Cα-NH-CO-Cα
d. NH-CO
e. NH-CO-Cα ✔Correct Answer-a. CαH-NH-CO-C-CαH
6 In the majority of α-helixes, each peptide carbonyl is hydrogen bonded to the peptide N-H group
______ residues farther _____ the chain.
a. 2, down
b. 4, up
c. 3, down
d. 2, up
e. 4, down ✔Correct Answer-a. 2, down
, 7 The amino acid residue most likely to be found in a beta turn is:
a. glycine.
b. alanine.
c. valine.
d. glutamic acid.
e. leucine. ✔Correct Answer-a. glycine.
Tertiary structure is defined as:
a. the sequence of amino acids.
b. the folding of a single polypeptide chain in three-dimensional space.
c. hydrogen bonding interactions between adjacent amino acid residues into helical or pleated
segments.
d. the way in which separate folded monomeric protein subunits associate to form oligomeric
proteins.
e. all are true. ✔Correct Answer-b. the folding of a single polypeptide chain in three-dimensional
space.
The specific site on the enzyme where __________ binds and catalysis occurs is called the
_____________ site.
a. coenzyme; substrate
b. substrate; active
c. coenzyme; regulatory
d. regulatory; active
e. none of the above ✔Correct Answer-b. substrate; active
All are true for catalysts EXCEPT:
a. They work by lowering the energy of activation.
b. The average energy of the reaction is unchanged.
c. They combine transiently with the reactants promoting a reactive transition state condition.
d. They are regenerated after each reaction cycle.
e. All are true. ✔Correct Answer-e. All are true.
All are true for the enzyme-transition state complex EXCEPT:
a. It is designated as EX‡.
b. The enzyme stabilizes the transition-state complex more than it stabilizes the substrate complex.
c. The enzyme is "designed" to bind the transition-state structure more tightly than the substrate or
product.
d. The energy barrier between ES and EX‡ is less than the energy barrier between S and X‡.
e. All are true. ✔Correct Answer-b. The enzyme stabilizes the transition-state complex more than it
stabilizes the substrate complex.
12 Transition-state analogs are:
a. approximations of the transition state that bind more tightly than the substrate.
b. compounds that compete for the active site, but are not necessarily very similar to the substrate.
c. stable molecules that can not be expected to resemble the true transition state too closely.
d. stable chemically and structurally similar molecules to the transition state.
e. all of the above. ✔Correct Answer-d. stable chemically and structurally similar molecules to the
transition state.
13 All are characteristic of allosteric enzymes EXCEPT:
