Biochemistry Exam 2 | Biochemistry Module Exam 2 | Biochemistry ACTUAL
Exam 2 COMPLETE QUESTIONS WITH 100% RATED CORRECT
ANSWERS 2025 LATEST UPDATED GRADED A+| GET IT CORRECT!!
CHAPTER 6: ENZYMES - (answer)CHAPTER 6: ENZYMES
What are enzymes? - (answer)-They are biological catalysts (i.e. they increase reaction rates w/o
being used up).
-They are proteins:Some RNA molecules (ribozymes) can also catalyze chemical reactions
-Enzymes can use cofactors: Metal ions, Coenzymes (derived from vitamins), & Prosthetic group
(coenzyme that is covalently attached)
What is common and what is different between enzymes and inorganic catalysts? - (answer)
What are the advantages of the enzymes over inorganic catalysts? - (answer)-Milder reaction
conditions (cell environment: 37˚C, pH~7.0)
-Higher reaction rates (in a biologically useful timeframe)
-Capacity for regulation (control of biological pathways)
-Greater reaction specificity (no side products)
What are the cofactors that can help enzymes catalyze their reactions? - (answer)Metal ions,
coenzymes, and prosthetic groups.
Define the following words: Apoenzyme, coenzyme, holoenzyme, & prosthetic group. -
(answer)-Apoenzyme: an inactive enzyme, activation of the enzyme occurs upon binding of an
organic or inorganic cofactor
-Coenzyme: a complex organic or metalloorganic molecule; Most are derived from vitamins
-Holoenzyme: ApoEnzyme + Cofactor; the enzyme is complete and catalytically active
,-Prosthetic group:A coenzyme or metal ion that is very tightly or even covalently bound to the
enzyme protein
What are the factors that can affect activity of enzymes? - (answer)-Temperature
-pH
-Ionic strength
-Presence of cofactors & prosthetic groups
What happens to enzymes at high and low temperatures? pH? - (answer)-At high temperatures
the enzyme gets denatured.
-At low temperatures the enzyme becomes inactive
How do enzymes work? Define the following: Substrate, product, enzyme's active site, activation
energy, transition state. - (answer)Enzymes act by binding substrates into their active sites.
-Substrate: Molecule acted upon by an enzyme
-Active site: Pocket on enzyme where reactions occur
-General enzymatic reaction: E + S <-> ES <-> EP <-> E + P
-Enzymes increase reaction rate by lowering activation energy
Is the chemical equilibrium affected during enzyme-catalyzed reaction? - (answer)Enzymes do
not affect equilibrium (ΔG)
What happens with the rates of forward and reverse reactions during enzyme catalysis? -
(answer)Enzymes equally increase reaction rates of both forward and reverse reactions
, What happens with the activation energy during enzyme-catalyzed reaction? - (answer)-Enzymes
increase reaction rates (k) by decreasing activation energy ΔG‡
-Slow reactions are characterized by high activation energy (ΔG‡) that must be surmounted
during the reaction
What are the ways to lower the activation energy in chemical reactions? - (answer)Enzyme uses
the binding energy of substrates to organize the reactants to a fairly rigid ES complex
-Entropy cost is paid during binding
-Rigid reactant complex transition state conversion is entropically OK
Role of binding energy in catalysis? - (answer)Weak binding interactions between the enzyme
and the substrate provide a substantial driving force for enzymatic catalysis.
Prominent physical & thermodynamic factors contributing to activation energy: -Entropy
(freedom of motion) of molecules in solution.
-Solvation (H bonded water molecules surrounding substrate)
-Distortion of substrate molecules
-Proper alignment
-Binding energy can be used to overcome all these but it is only one of several contributors to the
overall catalytic mechanism
Describe the 4 main types of catalytic mechanisms: acid-base catalysis, covalent
catalysis, metal-ion catalysis, and electrostatic catalysis - (answer)Acid-base catalysis: give and
take protons
Covalent catalysis: a transient covalent bond btwn enzyme & substrate that changes reaction
paths; requires a nucleophile on the enzyme (can be a reactive serine, thiolate, amine, or
carboxylate)
Metal ion catalysis: use redox cofactors, pKa shifters; involves a metal ion bound to the enzyme,
interacts w/substrate to facilitate binding, & participates in oxidation reactions
Exam 2 COMPLETE QUESTIONS WITH 100% RATED CORRECT
ANSWERS 2025 LATEST UPDATED GRADED A+| GET IT CORRECT!!
CHAPTER 6: ENZYMES - (answer)CHAPTER 6: ENZYMES
What are enzymes? - (answer)-They are biological catalysts (i.e. they increase reaction rates w/o
being used up).
-They are proteins:Some RNA molecules (ribozymes) can also catalyze chemical reactions
-Enzymes can use cofactors: Metal ions, Coenzymes (derived from vitamins), & Prosthetic group
(coenzyme that is covalently attached)
What is common and what is different between enzymes and inorganic catalysts? - (answer)
What are the advantages of the enzymes over inorganic catalysts? - (answer)-Milder reaction
conditions (cell environment: 37˚C, pH~7.0)
-Higher reaction rates (in a biologically useful timeframe)
-Capacity for regulation (control of biological pathways)
-Greater reaction specificity (no side products)
What are the cofactors that can help enzymes catalyze their reactions? - (answer)Metal ions,
coenzymes, and prosthetic groups.
Define the following words: Apoenzyme, coenzyme, holoenzyme, & prosthetic group. -
(answer)-Apoenzyme: an inactive enzyme, activation of the enzyme occurs upon binding of an
organic or inorganic cofactor
-Coenzyme: a complex organic or metalloorganic molecule; Most are derived from vitamins
-Holoenzyme: ApoEnzyme + Cofactor; the enzyme is complete and catalytically active
,-Prosthetic group:A coenzyme or metal ion that is very tightly or even covalently bound to the
enzyme protein
What are the factors that can affect activity of enzymes? - (answer)-Temperature
-pH
-Ionic strength
-Presence of cofactors & prosthetic groups
What happens to enzymes at high and low temperatures? pH? - (answer)-At high temperatures
the enzyme gets denatured.
-At low temperatures the enzyme becomes inactive
How do enzymes work? Define the following: Substrate, product, enzyme's active site, activation
energy, transition state. - (answer)Enzymes act by binding substrates into their active sites.
-Substrate: Molecule acted upon by an enzyme
-Active site: Pocket on enzyme where reactions occur
-General enzymatic reaction: E + S <-> ES <-> EP <-> E + P
-Enzymes increase reaction rate by lowering activation energy
Is the chemical equilibrium affected during enzyme-catalyzed reaction? - (answer)Enzymes do
not affect equilibrium (ΔG)
What happens with the rates of forward and reverse reactions during enzyme catalysis? -
(answer)Enzymes equally increase reaction rates of both forward and reverse reactions
, What happens with the activation energy during enzyme-catalyzed reaction? - (answer)-Enzymes
increase reaction rates (k) by decreasing activation energy ΔG‡
-Slow reactions are characterized by high activation energy (ΔG‡) that must be surmounted
during the reaction
What are the ways to lower the activation energy in chemical reactions? - (answer)Enzyme uses
the binding energy of substrates to organize the reactants to a fairly rigid ES complex
-Entropy cost is paid during binding
-Rigid reactant complex transition state conversion is entropically OK
Role of binding energy in catalysis? - (answer)Weak binding interactions between the enzyme
and the substrate provide a substantial driving force for enzymatic catalysis.
Prominent physical & thermodynamic factors contributing to activation energy: -Entropy
(freedom of motion) of molecules in solution.
-Solvation (H bonded water molecules surrounding substrate)
-Distortion of substrate molecules
-Proper alignment
-Binding energy can be used to overcome all these but it is only one of several contributors to the
overall catalytic mechanism
Describe the 4 main types of catalytic mechanisms: acid-base catalysis, covalent
catalysis, metal-ion catalysis, and electrostatic catalysis - (answer)Acid-base catalysis: give and
take protons
Covalent catalysis: a transient covalent bond btwn enzyme & substrate that changes reaction
paths; requires a nucleophile on the enzyme (can be a reactive serine, thiolate, amine, or
carboxylate)
Metal ion catalysis: use redox cofactors, pKa shifters; involves a metal ion bound to the enzyme,
interacts w/substrate to facilitate binding, & participates in oxidation reactions
