BCH403 FINAL EXAMINATION
QUESTIONS WITH CORRECT
DETAILED ANSWERS
A membrane channel required for the controlled transport of a compound [S] is found to
contain a mutation that disrupts (weakens) binding to the compound. Which of the
following transport kinetics curves will this protein now display?
- curve A
- curve b
- curve c
- non of the curves describe the new kinetics - Answer-- curve c
which of the following are not steps in the "signal hypothesis"
- recognition of the N-terminal signal sequence by the SRP
- binding of the SRP to the SRP receptor
- Hydrolysis of GTP into GDP + Pi
- Temporary halting of protein translation when the ribosome is bound to the SRP
- All are steps in the signal hypothesis - Answer-- all are steps in the signal hypothesis
the burst kinetics displayed by chymotrypsin in hydrolysis of p-nitrophenylacetate
demonstrate that:
- the rate-determining step is acylation of the enzyme
- the rate - determining step is deacylation of the enzyme
- the rate- determining step is the initial binding of substrate
- the rate-determining step is hydrolysis of the ester bond
- non of the above - Answer-- the rate-determining step is deacylation of the enzyme
The composition of the bilayer has been modified to include 10 % cholesterol. Which of
the following is true regarding the new properties of the bilayer
- the Tm of the bilayer is increased
- the Tm of bilayer has not changed
- the rigidity of the cholesterol broadens the transition temperature of the bilayer
- A and C
- B and C - Answer-- B and C
- the Tm of the bilayer has not changed
- The rigidity of the cholesterol broadens the transition temperature of the bilayer
An integration membrane protein that is expected to be on the plama membrane is
instead found in the cytoplasm. Which of the following would explain this result.
,- a protein transporter has becoem defective
- the signal peptidase in the ER lumen is no longer working
- the SRP is not able to recognize the N-terminal signal sequence
- the translocon is not able to recognize the C-terminal signal sequence
- the fluidity of the plasma membrane has been altered - Answer-- the SRP is not able
to recognize the N-terminal signal sequence
What might occur if the Zn2+ prosthetic group was no longer present in the enzyme
carboxypeptidase A during a reaction?
- the delta G would increase
- the Delta G would decrease
- the burst phase would reach steady-state at a faster rate
- the delta g would remain unchanged
- b and c - Answer-- the delta g would increase
T/F: Anabolic pathways require an energy input to synthesize more complex molecules
from less complex molecules - Answer-True
T/F: Phosphoenolpyruvate carboxykinase is found within the mitochondria - Answer-
False
T/F: Fructose-2,6-bisphosphate inactivates fructose-1,6-bisphosphatase by directly
binding to the active site of the enzyme (i.e., it's a competitive inhibitor) - Answer-False
T/F: Malate/Asparate shuttle is used by the liver to transport two electrons from
cytosolic NADH onto mitochondrial NADH - Answer-True
T/F: Succinate dehydrogenase complex draws two electrons away from succinate and
donates them to coenzyme Q - Answer-True
T/F: Hexokinase phosphorylates glucose so that glucose can not be transported out of
the cell - Answer-True
T/F: During glycogenolysis, debranching enzymes can synthesize a(1-->4) linkages -
Answer-False
T/F: The majority of lactate in the average human body is produced in cardiac muscles -
Answer-false
T/F: Hydrogen peroxide is formed during respiration when one electron is transferred to
O2 - Answer-False
T/F: Insulin does not activate every biochemical pathway that leads to the complete
oxidation of glucose - Answer-True
, A biochemical reaction that requires ATP input has a delta G' = -33.4 kJ/mol. Which one
of the following is most likely to be true?
- This biochemical reaction is exergonic and reversible
- This biochemical reaction is at equilibrium and reversible
- this biochemical reaction is endergonic and irreversible
- This biochemical reaction is exergonic and irreversible
- this biochemical reaction is at equilibrium and reversible - Answer-- this biochemical
reaction is exergonic and irreversible
Which one of the following enzymes synthesizes ATP using chemical (heat) energy?
- Pyruvate Kinase
- Hexokinase
- ATP Synthase
- Fructose-1,6-bisphosphatase
- Pyruvate dehydrogenase - Answer-- Pyruvate Kinase
Which one of the following enzymes is required to bypass phosphofructokinase -1 when
synthesizing glucose?
- Phosphofructokinase-2
- Glucose-6- Phosphatase
- Fructose-1,6-bisphosphatase
- phosphoenolpyruvate carboxykinase
- pyruvate decarboxylase - Answer-Fructose-1,6-bisphosphatase
Which one of the following enzymes catalyze the synthesis of a(1-->4) glucose linkages
in glycogen?
- a-amylase
- glycogen phosphorylase
-glycogen synthase
- branching enzyme
- phosphoglucoisomerase - Answer-- glycogen synthase
Which one of the following enzymes is NOT controlled by glucagon?
- Pyruvate Kinase
- Phosphofructokinase-1
- Glycogen Phosphorylase
- Glycogen synthase
- Hexokinase - Answer-Hexokinase
Which one of the following statements is incorrect regarding citrate synthase?
QUESTIONS WITH CORRECT
DETAILED ANSWERS
A membrane channel required for the controlled transport of a compound [S] is found to
contain a mutation that disrupts (weakens) binding to the compound. Which of the
following transport kinetics curves will this protein now display?
- curve A
- curve b
- curve c
- non of the curves describe the new kinetics - Answer-- curve c
which of the following are not steps in the "signal hypothesis"
- recognition of the N-terminal signal sequence by the SRP
- binding of the SRP to the SRP receptor
- Hydrolysis of GTP into GDP + Pi
- Temporary halting of protein translation when the ribosome is bound to the SRP
- All are steps in the signal hypothesis - Answer-- all are steps in the signal hypothesis
the burst kinetics displayed by chymotrypsin in hydrolysis of p-nitrophenylacetate
demonstrate that:
- the rate-determining step is acylation of the enzyme
- the rate - determining step is deacylation of the enzyme
- the rate- determining step is the initial binding of substrate
- the rate-determining step is hydrolysis of the ester bond
- non of the above - Answer-- the rate-determining step is deacylation of the enzyme
The composition of the bilayer has been modified to include 10 % cholesterol. Which of
the following is true regarding the new properties of the bilayer
- the Tm of the bilayer is increased
- the Tm of bilayer has not changed
- the rigidity of the cholesterol broadens the transition temperature of the bilayer
- A and C
- B and C - Answer-- B and C
- the Tm of the bilayer has not changed
- The rigidity of the cholesterol broadens the transition temperature of the bilayer
An integration membrane protein that is expected to be on the plama membrane is
instead found in the cytoplasm. Which of the following would explain this result.
,- a protein transporter has becoem defective
- the signal peptidase in the ER lumen is no longer working
- the SRP is not able to recognize the N-terminal signal sequence
- the translocon is not able to recognize the C-terminal signal sequence
- the fluidity of the plasma membrane has been altered - Answer-- the SRP is not able
to recognize the N-terminal signal sequence
What might occur if the Zn2+ prosthetic group was no longer present in the enzyme
carboxypeptidase A during a reaction?
- the delta G would increase
- the Delta G would decrease
- the burst phase would reach steady-state at a faster rate
- the delta g would remain unchanged
- b and c - Answer-- the delta g would increase
T/F: Anabolic pathways require an energy input to synthesize more complex molecules
from less complex molecules - Answer-True
T/F: Phosphoenolpyruvate carboxykinase is found within the mitochondria - Answer-
False
T/F: Fructose-2,6-bisphosphate inactivates fructose-1,6-bisphosphatase by directly
binding to the active site of the enzyme (i.e., it's a competitive inhibitor) - Answer-False
T/F: Malate/Asparate shuttle is used by the liver to transport two electrons from
cytosolic NADH onto mitochondrial NADH - Answer-True
T/F: Succinate dehydrogenase complex draws two electrons away from succinate and
donates them to coenzyme Q - Answer-True
T/F: Hexokinase phosphorylates glucose so that glucose can not be transported out of
the cell - Answer-True
T/F: During glycogenolysis, debranching enzymes can synthesize a(1-->4) linkages -
Answer-False
T/F: The majority of lactate in the average human body is produced in cardiac muscles -
Answer-false
T/F: Hydrogen peroxide is formed during respiration when one electron is transferred to
O2 - Answer-False
T/F: Insulin does not activate every biochemical pathway that leads to the complete
oxidation of glucose - Answer-True
, A biochemical reaction that requires ATP input has a delta G' = -33.4 kJ/mol. Which one
of the following is most likely to be true?
- This biochemical reaction is exergonic and reversible
- This biochemical reaction is at equilibrium and reversible
- this biochemical reaction is endergonic and irreversible
- This biochemical reaction is exergonic and irreversible
- this biochemical reaction is at equilibrium and reversible - Answer-- this biochemical
reaction is exergonic and irreversible
Which one of the following enzymes synthesizes ATP using chemical (heat) energy?
- Pyruvate Kinase
- Hexokinase
- ATP Synthase
- Fructose-1,6-bisphosphatase
- Pyruvate dehydrogenase - Answer-- Pyruvate Kinase
Which one of the following enzymes is required to bypass phosphofructokinase -1 when
synthesizing glucose?
- Phosphofructokinase-2
- Glucose-6- Phosphatase
- Fructose-1,6-bisphosphatase
- phosphoenolpyruvate carboxykinase
- pyruvate decarboxylase - Answer-Fructose-1,6-bisphosphatase
Which one of the following enzymes catalyze the synthesis of a(1-->4) glucose linkages
in glycogen?
- a-amylase
- glycogen phosphorylase
-glycogen synthase
- branching enzyme
- phosphoglucoisomerase - Answer-- glycogen synthase
Which one of the following enzymes is NOT controlled by glucagon?
- Pyruvate Kinase
- Phosphofructokinase-1
- Glycogen Phosphorylase
- Glycogen synthase
- Hexokinase - Answer-Hexokinase
Which one of the following statements is incorrect regarding citrate synthase?
