BCH 361 EXAM 2 Study Questions with 100%
Correct Verified Solutions| Latest Update
The ΔG of a reaction depends only on the free energy of the products (the final state)
minus - Answer the free energy of the reactants (the initial state). The ΔG of a reaction is
independent of the path (or molecular mechanism) of the transformation. The
mechanism of a reaction has no effect on ΔG.
The ΔG provides no information about the rate of a reaction. - Answer A negative ΔG
indicates that a reaction can take place spontaneously, but it does not signify whether it
will proceed at a perceptible rate.
It is important to stress that whether the ΔG for a reaction is larger, smaller, or the same
as ΔG°′ depends on - Answer the concentration of the products and reactants
An enzyme cannot alter the laws of thermodynamics and consequently cannot alter -
Answer the equilibrium of a chemical reaction
Enzymes accelerate the attainment of equilibria but do not shift their positions. The
equilibrium position is a function only of - Answer the free-energy difference between
reactants and products.
the transition state has one of the highest - Answer free energy
The difference in free energy between the transition state and the substrate is called
the - Answer activation energy
enzymes function to lower the activation energy. In other words - Answer enzymes
facilitate the formation of the transition state
,enzymes facilitate the formation of the transition state by - Answer lowering the
activation energy
The interaction of the enzyme and substrate at the active site promotes - Answer the
formation of the transition state
Common features of the active site: (5 points) - Answer 1. The active site is a three-
dimensional cleft or crevice
2. The active site takes up a small part of the total volume of an enzyme.
3. Active sites are unique micro environments.
4. Substrates are bound to enzymes by multiple weak attractions.
5. The specificity of binding depends on the precisely defined arrangement of atoms in
an active site.
The free energy released on binding is called - Answer binding energy
the maximal binding energy is released when - Answer the enzyme facilitates the
formation of the transition state
What are the two properties of enzymes that make them especially useful catalysts? -
Answer rate enhancement and substrate specificity
What does an apoenzyme require to become a holoenzyme? - Answer a cofactor
What is the fundamental mechanism by which enzymes enhance the rate of chemical
reactions? - Answer Enzymes facilitate the formation of the transition state.
,What is meant by the term binding energy? - Answer Binding energy is the free energy
released when two molecules bind together, such as when an enzyme and a substrate
interact.
What is the role of binding energy in enzyme catalysis? - Answer Binding energy is
maximized when an enzyme interacts with the transition state, thereby facilitating the
formation of the transition state and enhancing the rate of the reaction.
What would be the result of an enzyme having a greater binding energy for the
substrate than for the transition state? - Answer there would be no catalytic activity
Why does the activation energy of a reaction not appear in the final ΔG of the reaction?
- Answer The energy required to reach the transition state (the activation energy) is
returned when the transition state proceeds to product.
three things that characterize enzymes - Answer 1. catalytic power
2. specificity to substrate
3. type of reaction
The proteolytic enzymes have different degrees of specificity, ranging from unspecific to
very specific.
List the four proteolytic enzymes - Answer 1. Papain (found in papaya plant) is quite
undiscriminating. (meat tenderizer)
2. Trypsin (found in human small intestine) is quite specific, it splits the peptide bonds
only on the carboxyl side of lysine and arginine (positively charged) residues.
3. Chymotrypsin is similar, but splits the peptide bonds only on the carboxyl side of large
hydrophobic residues.
, 4. Thrombin (in blood clotting) is even more specific, it catalyze the hydrolysis of Arg-Gly
bonds in particular peptide sequence only.
The criterion of spontaneity for a reaction _____ not _____ - Answer is ΔG, not ΔGo',
and can be made spontaneous by adjusting the concentrations of the reactants and
products.
This is the basis of coupling of reactions in metabolic pathways.
The reaction equilibrium is determined only by - Answer the free energy difference
between the products and reactants (ΔG).
Enzymes cannot alter this free energy difference, thus does not change the reaction
equilibrium, but only the rate to reach the equilibrium.
systematic classification numbers for enzymes (there are 4) - Answer 1. is a member of
hydrolyases (class 3)
2. cleaves peptide bonds (subgroup 4)
3. employs a serine residue at active site to facilitate hydrolysis (sub-sub group 21)
4. cleaves peptide bond on the carbonyl side of lysine or arginine (sub-sub-sub group 4)
-the uniques ID of trypsin is 3.4.21.4
Enzymes accelerate the reaction rate but do not alter - Answer the equilibrium
The same equilibrium point is reached, but much more quickly in the presence of an
enzyme.
Correct Verified Solutions| Latest Update
The ΔG of a reaction depends only on the free energy of the products (the final state)
minus - Answer the free energy of the reactants (the initial state). The ΔG of a reaction is
independent of the path (or molecular mechanism) of the transformation. The
mechanism of a reaction has no effect on ΔG.
The ΔG provides no information about the rate of a reaction. - Answer A negative ΔG
indicates that a reaction can take place spontaneously, but it does not signify whether it
will proceed at a perceptible rate.
It is important to stress that whether the ΔG for a reaction is larger, smaller, or the same
as ΔG°′ depends on - Answer the concentration of the products and reactants
An enzyme cannot alter the laws of thermodynamics and consequently cannot alter -
Answer the equilibrium of a chemical reaction
Enzymes accelerate the attainment of equilibria but do not shift their positions. The
equilibrium position is a function only of - Answer the free-energy difference between
reactants and products.
the transition state has one of the highest - Answer free energy
The difference in free energy between the transition state and the substrate is called
the - Answer activation energy
enzymes function to lower the activation energy. In other words - Answer enzymes
facilitate the formation of the transition state
,enzymes facilitate the formation of the transition state by - Answer lowering the
activation energy
The interaction of the enzyme and substrate at the active site promotes - Answer the
formation of the transition state
Common features of the active site: (5 points) - Answer 1. The active site is a three-
dimensional cleft or crevice
2. The active site takes up a small part of the total volume of an enzyme.
3. Active sites are unique micro environments.
4. Substrates are bound to enzymes by multiple weak attractions.
5. The specificity of binding depends on the precisely defined arrangement of atoms in
an active site.
The free energy released on binding is called - Answer binding energy
the maximal binding energy is released when - Answer the enzyme facilitates the
formation of the transition state
What are the two properties of enzymes that make them especially useful catalysts? -
Answer rate enhancement and substrate specificity
What does an apoenzyme require to become a holoenzyme? - Answer a cofactor
What is the fundamental mechanism by which enzymes enhance the rate of chemical
reactions? - Answer Enzymes facilitate the formation of the transition state.
,What is meant by the term binding energy? - Answer Binding energy is the free energy
released when two molecules bind together, such as when an enzyme and a substrate
interact.
What is the role of binding energy in enzyme catalysis? - Answer Binding energy is
maximized when an enzyme interacts with the transition state, thereby facilitating the
formation of the transition state and enhancing the rate of the reaction.
What would be the result of an enzyme having a greater binding energy for the
substrate than for the transition state? - Answer there would be no catalytic activity
Why does the activation energy of a reaction not appear in the final ΔG of the reaction?
- Answer The energy required to reach the transition state (the activation energy) is
returned when the transition state proceeds to product.
three things that characterize enzymes - Answer 1. catalytic power
2. specificity to substrate
3. type of reaction
The proteolytic enzymes have different degrees of specificity, ranging from unspecific to
very specific.
List the four proteolytic enzymes - Answer 1. Papain (found in papaya plant) is quite
undiscriminating. (meat tenderizer)
2. Trypsin (found in human small intestine) is quite specific, it splits the peptide bonds
only on the carboxyl side of lysine and arginine (positively charged) residues.
3. Chymotrypsin is similar, but splits the peptide bonds only on the carboxyl side of large
hydrophobic residues.
, 4. Thrombin (in blood clotting) is even more specific, it catalyze the hydrolysis of Arg-Gly
bonds in particular peptide sequence only.
The criterion of spontaneity for a reaction _____ not _____ - Answer is ΔG, not ΔGo',
and can be made spontaneous by adjusting the concentrations of the reactants and
products.
This is the basis of coupling of reactions in metabolic pathways.
The reaction equilibrium is determined only by - Answer the free energy difference
between the products and reactants (ΔG).
Enzymes cannot alter this free energy difference, thus does not change the reaction
equilibrium, but only the rate to reach the equilibrium.
systematic classification numbers for enzymes (there are 4) - Answer 1. is a member of
hydrolyases (class 3)
2. cleaves peptide bonds (subgroup 4)
3. employs a serine residue at active site to facilitate hydrolysis (sub-sub group 21)
4. cleaves peptide bond on the carbonyl side of lysine or arginine (sub-sub-sub group 4)
-the uniques ID of trypsin is 3.4.21.4
Enzymes accelerate the reaction rate but do not alter - Answer the equilibrium
The same equilibrium point is reached, but much more quickly in the presence of an
enzyme.
