Metabolic Biochemistry Exam 1
UPDATED ACTUAL Exam Questions and
CORRECT Answers
How do allosteric effectors affect enzyme structure and function? - CORRECT
ANSWER✔✔- "from a distance"
allosteric inhibitors can either activate or deactivate an enzyme.
Example of allosteric inhibitor - CORRECT ANSWER✔✔- ATP = allosteric I for ATCase.
Give overview of glycogen phosphorylase covalent modification - CORRECT
ANSWER✔✔- (glycogen)n +PO4 -> (glycogen)n-1 and G6P
How does covalent modification affect the T and R state for glycogen phosphorylase? -
CORRECT ANSWER✔✔- Phosphorylated form favors the R-state (active)
Dephosphorylated form favors the T-state (inactive)
Reasons why T-state of glycogen phosphorylase is inactive - CORRECT ANSWER✔✔- 1.
Loop blocks the active site so substrate cannot bind.
2. Malformed active site: misaligned Arg for phosphate substrate binding.
3. Ser14 is not near allosteric Arg.
Reasons why R-state of glycogen phosphorylase is active. - CORRECT ANSWER✔✔- 1.
Active site not blocked by loop due to flexibility.
2. Arg properly aligned to bind to phosphate.
3. Ser-phosphate goes through conformational change to be near allosteric site.
What condition to metabolic pathways function under? - CORRECT ANSWER✔✔- Steady-
state: constant input of reactants.
What type of Delta G does an enzyme that functions near equilibrium have? - CORRECT
ANSWER✔✔- Near-equil. = no reactant buildup
, so Q~Keq so Delta G ~0.
Small change in [reactant] leads to change in Delta G sign and direction of reaction.
What type of Delta G does an enzyme that functions far from equilibrium have? - CORRECT
ANSWER✔✔- Large neg. Delta G
Too slow to maintain equil [R] and [R] and is irreversible.
Q<<<<<<Keq so Delta G <<<<<0
Changes in [R] do not alter G significantly.
Define "high-energy" compounds - CORRECT ANSWER✔✔- "packets" of energy (large
neg. Delta G) are conserved by the synthesis of a few types of "high-energy" intermediates
whose subsequent exergonic breakdown drives endergonic processes.
Four example of "high-energy" compounds. - CORRECT ANSWER✔✔- Pyrophosphates
Acylphosphates
Thiolesters
Phosphoguanadines
Factors that contribute to high energy of pyrophosphate - CORRECT ANSWER✔✔- 1.
Resonance competition relieved with hydrolysis.
2. Electrostatic repulsion is relieved in hydrolysis.
3. More favorable solvation energy of hydrolysis products.
Factors that contribute to high energy of acylphosphates - CORRECT ANSWER✔✔- 1.
Resonance competition relieved with hydrolysis.
3. More favorable solvation energy of hydrolysis products.
Factors that contribute to high energy of thiolesters - CORRECT ANSWER✔✔- 3. More
favorable solvation energy of hydrolysis products.
3 reasons why energy is released when bond is hydrolyzed. - CORRECT ANSWER✔✔- 1.
Resonance stabilization of hydrolysis products is greater than the reactant.
UPDATED ACTUAL Exam Questions and
CORRECT Answers
How do allosteric effectors affect enzyme structure and function? - CORRECT
ANSWER✔✔- "from a distance"
allosteric inhibitors can either activate or deactivate an enzyme.
Example of allosteric inhibitor - CORRECT ANSWER✔✔- ATP = allosteric I for ATCase.
Give overview of glycogen phosphorylase covalent modification - CORRECT
ANSWER✔✔- (glycogen)n +PO4 -> (glycogen)n-1 and G6P
How does covalent modification affect the T and R state for glycogen phosphorylase? -
CORRECT ANSWER✔✔- Phosphorylated form favors the R-state (active)
Dephosphorylated form favors the T-state (inactive)
Reasons why T-state of glycogen phosphorylase is inactive - CORRECT ANSWER✔✔- 1.
Loop blocks the active site so substrate cannot bind.
2. Malformed active site: misaligned Arg for phosphate substrate binding.
3. Ser14 is not near allosteric Arg.
Reasons why R-state of glycogen phosphorylase is active. - CORRECT ANSWER✔✔- 1.
Active site not blocked by loop due to flexibility.
2. Arg properly aligned to bind to phosphate.
3. Ser-phosphate goes through conformational change to be near allosteric site.
What condition to metabolic pathways function under? - CORRECT ANSWER✔✔- Steady-
state: constant input of reactants.
What type of Delta G does an enzyme that functions near equilibrium have? - CORRECT
ANSWER✔✔- Near-equil. = no reactant buildup
, so Q~Keq so Delta G ~0.
Small change in [reactant] leads to change in Delta G sign and direction of reaction.
What type of Delta G does an enzyme that functions far from equilibrium have? - CORRECT
ANSWER✔✔- Large neg. Delta G
Too slow to maintain equil [R] and [R] and is irreversible.
Q<<<<<<Keq so Delta G <<<<<0
Changes in [R] do not alter G significantly.
Define "high-energy" compounds - CORRECT ANSWER✔✔- "packets" of energy (large
neg. Delta G) are conserved by the synthesis of a few types of "high-energy" intermediates
whose subsequent exergonic breakdown drives endergonic processes.
Four example of "high-energy" compounds. - CORRECT ANSWER✔✔- Pyrophosphates
Acylphosphates
Thiolesters
Phosphoguanadines
Factors that contribute to high energy of pyrophosphate - CORRECT ANSWER✔✔- 1.
Resonance competition relieved with hydrolysis.
2. Electrostatic repulsion is relieved in hydrolysis.
3. More favorable solvation energy of hydrolysis products.
Factors that contribute to high energy of acylphosphates - CORRECT ANSWER✔✔- 1.
Resonance competition relieved with hydrolysis.
3. More favorable solvation energy of hydrolysis products.
Factors that contribute to high energy of thiolesters - CORRECT ANSWER✔✔- 3. More
favorable solvation energy of hydrolysis products.
3 reasons why energy is released when bond is hydrolyzed. - CORRECT ANSWER✔✔- 1.
Resonance stabilization of hydrolysis products is greater than the reactant.
