BMSC 200 Module 6 Exam Questions
with Complete Answers
lyases - ANSWER-addition of groups to double bonds, or formation of double bonds
by removal of groups
isomerases - ANSWER-Transfer of groups within molecules to yield isomeric forms
(moving a functional group but in same unit)
ligases - ANSWER-formation of C-C, C-S, C-O, and C-N bonds by condensation
reactions coupled to cleavage of ATP or similar cofactor
catalysts do what? - ANSWER-- lower the amount of energy required for a reaction
to proceed (make things happen faster)
- speed up attainment of equilibrium (rate of reaction) but do not change equilibrium
- are unchanged by the reaction; recycled to participate (multiple times, has to be
able to convert multiple substrates)
enzymes vs chemical catalysts - ANSWER-1. Faster: enzymes posses remarkable
catalytic power, some approaching catalytic perfection
2. Milder Conditions: many chemical catalysts that require extremes of temperature,
pressure and pH, enzymes function at physiological conditions
3. Greater Specificity: enzymes have a higher degree of specificity, including
stereospecificity for what they act upon and produce
4. Potential to be Regulated: many enzymes are responsive to the dynamic needs of
the cells and organism
Catalytic Power of Enzymes - ANSWER-- enzymes rates can approach the physical
limit of the rate of diffusion of two molecules in solution
- some enzymes have rate-determining steps that are roughly as fast as the binding
of substrates to the enzymes
- circe effect allows some enzymes to catalyze reaction faster than predicted by
diffusion-control limits
how enzymes work - ANSWER-enzymes catalyze the interconversion of substrate
and product
substrate (s) - ANSWER-the molecule to be acted upon by the enzyme, the input to
enzymatic reactions
product (p) - ANSWER-what is produced by the enzyme
active site - ANSWER-the portion of the enzyme (E) responsible for binding the
substrate leading to the formation of an enzyme-substrate (ES) complex
, activation energy, delta G between S and P determines what - ANSWER-rate at
which equilibrium is reached
enzymes provide what - ANSWER-an alternate, lower-energy pathway between the
substrate and product, lowering delta G
the relationship between the rate of a reaction and the activation energy is -
ANSWER-inverse and exponential
difference in free energy delta G between S and P determines - ANSWER-the
equilibrium of the reactions, enzymes don't influence delta G' o
enzymes _________ the activation energy of the transition state - ANSWER-
decrease
enzymes _____ the rates of a reaction - ANSWER-increase
enzymes ________ affect the equilibrium of a reaction - ANSWER-do not
what are the forces that contribute to the lowering of the activation energy? -
ANSWER-catalytic capabilities of enzymes result from chemical effects and binding
properties
binding effects - ANSWER-the physical interaction between substrate and enzyme
- substrate binding
- transition-state stabilization
chemical effects - ANSWER-the enzyme actually does stuff to the molecule
- acid-base catalysis
- covalent catalysis
binding of reactants in enzyme active sites provides - ANSWER-substrate specificity
and catalytic power
catalytic mechanisms limited to binding properties can increase reaction rates by? -
ANSWER-over 10,000- fold
there is __________ ________ between substrate binding and transition state
stabilization - ANSWER-conceptual overlap
enzymes properly gather and position substrates, this.... - ANSWER-makes the
formation of the transition state more frequent and lowers the energy of activation
substrate binding promotes reactions by: - ANSWER-- reducing the entropy
(decreased freedom of motion of two molecules in solution)
- desolvation of the substrate to expose reactive groups
- alignment of reactive functional groups of the enzyme with the substrate
- distortion of substrates, changing the conformation to make it more reacted
- induced fit of the enzyme in response to substrate binding (hand in glove)
with Complete Answers
lyases - ANSWER-addition of groups to double bonds, or formation of double bonds
by removal of groups
isomerases - ANSWER-Transfer of groups within molecules to yield isomeric forms
(moving a functional group but in same unit)
ligases - ANSWER-formation of C-C, C-S, C-O, and C-N bonds by condensation
reactions coupled to cleavage of ATP or similar cofactor
catalysts do what? - ANSWER-- lower the amount of energy required for a reaction
to proceed (make things happen faster)
- speed up attainment of equilibrium (rate of reaction) but do not change equilibrium
- are unchanged by the reaction; recycled to participate (multiple times, has to be
able to convert multiple substrates)
enzymes vs chemical catalysts - ANSWER-1. Faster: enzymes posses remarkable
catalytic power, some approaching catalytic perfection
2. Milder Conditions: many chemical catalysts that require extremes of temperature,
pressure and pH, enzymes function at physiological conditions
3. Greater Specificity: enzymes have a higher degree of specificity, including
stereospecificity for what they act upon and produce
4. Potential to be Regulated: many enzymes are responsive to the dynamic needs of
the cells and organism
Catalytic Power of Enzymes - ANSWER-- enzymes rates can approach the physical
limit of the rate of diffusion of two molecules in solution
- some enzymes have rate-determining steps that are roughly as fast as the binding
of substrates to the enzymes
- circe effect allows some enzymes to catalyze reaction faster than predicted by
diffusion-control limits
how enzymes work - ANSWER-enzymes catalyze the interconversion of substrate
and product
substrate (s) - ANSWER-the molecule to be acted upon by the enzyme, the input to
enzymatic reactions
product (p) - ANSWER-what is produced by the enzyme
active site - ANSWER-the portion of the enzyme (E) responsible for binding the
substrate leading to the formation of an enzyme-substrate (ES) complex
, activation energy, delta G between S and P determines what - ANSWER-rate at
which equilibrium is reached
enzymes provide what - ANSWER-an alternate, lower-energy pathway between the
substrate and product, lowering delta G
the relationship between the rate of a reaction and the activation energy is -
ANSWER-inverse and exponential
difference in free energy delta G between S and P determines - ANSWER-the
equilibrium of the reactions, enzymes don't influence delta G' o
enzymes _________ the activation energy of the transition state - ANSWER-
decrease
enzymes _____ the rates of a reaction - ANSWER-increase
enzymes ________ affect the equilibrium of a reaction - ANSWER-do not
what are the forces that contribute to the lowering of the activation energy? -
ANSWER-catalytic capabilities of enzymes result from chemical effects and binding
properties
binding effects - ANSWER-the physical interaction between substrate and enzyme
- substrate binding
- transition-state stabilization
chemical effects - ANSWER-the enzyme actually does stuff to the molecule
- acid-base catalysis
- covalent catalysis
binding of reactants in enzyme active sites provides - ANSWER-substrate specificity
and catalytic power
catalytic mechanisms limited to binding properties can increase reaction rates by? -
ANSWER-over 10,000- fold
there is __________ ________ between substrate binding and transition state
stabilization - ANSWER-conceptual overlap
enzymes properly gather and position substrates, this.... - ANSWER-makes the
formation of the transition state more frequent and lowers the energy of activation
substrate binding promotes reactions by: - ANSWER-- reducing the entropy
(decreased freedom of motion of two molecules in solution)
- desolvation of the substrate to expose reactive groups
- alignment of reactive functional groups of the enzyme with the substrate
- distortion of substrates, changing the conformation to make it more reacted
- induced fit of the enzyme in response to substrate binding (hand in glove)
