Download Review Questions for Advanced Biochemistry Course

Review Questions for Advanced Biochemistry
Course (Biotechnology)
Questions:
1. The enzyme of glycolysis that converts dihydroxyacetone phosphate to
glyceraldehyde-3-phosphate can be categorized into one of six types of enzymes. This
enzyme is most appropriately called a(n):
A.
B.
C.
D.
E.
Oxidoreductase
Transferase
Hydrolase
Lyase
Isomerase
2. On the following plot, N represents the curve for an allosteric enzyme with no
allosteric activators or inhibitors added. If an allosteric activator was added, which curve
would one obtain?
A.
B.
C.
D.
Curve A
Curve B
Curve C
Curve D
1
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
3. This small protein can have dramatic effects on the activities of enzymes in response to
changes in intracellular calcium ion concentration:
A.
B.
C.
D.
E.
Calcitonin
Calsequesterin
Calmodulin
Calcitriol
Calciferol
4. Which of the following statements about allosteric enzymes is CORRECT?
A.
B.
C.
D.
E.
The binding of substrate to any active site affects the other active sites
The plot of initial velocity vs. substrate concentration is a straight line
The Keq of the reaction is increased when allosteric activator is bound
The enzymes contains only one polypeptide chain
Allosteric activators bind to all active sites equally
5. The enzyme hexokinase is
A.
B.
C.
D.
E.
Usually found in liver
Uses fructose as a substrate
Requires sulfate as a substrate
Is found everywhere glucokinase is found
Is inhibited by glucose-6-phosphate
6. cAMP
A.
B.
C.
D.
E.
is created by the enzyme phosphodiesterase
is destroyed by the enzyme protein kinase A
is destroyed by the enzyme adenylate cyclase
will bind to the regulatory subunit of protein kinase A
increases in concentration whenever insulin is present.
7. Epinephrine binds to α1-receptors in the liver membrane. This binding
A. increases the concentration of phosphatidyl inositol trisphosphate in the
membrane
B. activates phospholipase C
C. decreases the concentration of diacylglycerol
D. increases calcium stored in the endoplasmic reticulum
E. inhibits protein kinase C
8.Assume the patient is fasting and then begins to eat a high carbohydrate meal.
Following an increase in blood glucose, the message of glucagon is, in part, terminated
by
2
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
A.
B.
C.
D.
E.
decreasing proteolysis in the liver
increasing glucagon release from alpha-cells of the pancreas
decreasing the GTPase activity of Gαs-stimulatory subunit
decreasing the cAMP phosphodiesterase activity
increasing protein phosphatase activity in the cell
9. Phosphorylase kinase activates muscle glycogen phosphorylase by
A.
B.
C.
D.
E.
Converting glycogen phosphorylase a to glycogen phosphorylase b
Phosphorylating a seryl residue on glycogen phosphorylase
Activating protein phosphatase
Binding to the AMP allosteric binding site
Acting as a negative allosteric effector
10. The alpha helix found in myoglobin can best be described as
A.
B.
C.
D.
E.
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
Motif structure
11. Apeptide bond is formed from a
A.
B.
C.
D.
E.
sulfhydryl group and a carboxyl group
carboxyl group and an amino group
phosphate group and an alcohol group
phosphate groupe and a carboxyl group
carboxyl group and another carboxyl group
12. For the enzyme reaction A+ B = C + D, Delta Go' = + 1 kcal/mol. This reaction will
proceed spontaneously in a forward direction if:
A.
B.
C.
D.
E.
The concentration of D is increased one-hundred fold
The concentration of C is increased one-hundred fold
The concentration of A is increased one-hundred fold
The concentration of B is lowered one-hundred fold
The concentration of both A and D are increased one-hundred fold
13. Oxidative phosphorylation:
A. Is anaerobic
B. Requires AMP
C. Requires the electron transport system
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Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
D. Is not dependent upon development of a proton gradient
E. Is independent of mitochondria
14. Which of the following is not a function of the citric acid cycle?
A.
B.
C.
D.
E.
Catabolism of carbon structures of some amino acids
Catabolism of acetate groups from acetyl CoA
The production of GTP
The production of NADPH
The production of carbon structures for the synthesis of some amino acids
15. In the citric acid cycle, a substrate level phosphorylation is catalyzed by:
A.
B.
C.
D.
E.
Citrate synthase
Succinyl CoA synthetase
Fumarase
Isocitrate dehydrogenase
Citrate lyase
16. In contrast to NADH, FAD(2H):
A.
B.
C.
D.
E.
Can donate electrons, but only two at a time, in a chemical reaction
Has a low affinity for its apoenzyme
Is very reactive in solution
Is an excellent feedback inhibitor
Is derived from a vitamin
17. Which of the following two enzymes are thought to be the major control enzymes of
the TCA cycle?
A.
B.
C.
D.
E.
Malate dehydrogenase and fumarase
Succinate dehydrogenase and fumarase
Succinyl CoA synthetase and succinate dehydrogenase
Succinyl CoA synthetase and alpha-ketoglutarate dehydrogenase
α-ketoglutarate dehydrogenase and isocitrate dehydrogenase
18. The ATP synthase responsible for most of the ATP synthesis in the body is located:
A.
B.
C.
D.
E.
On the outer side of the outer mitochondria membrane
On the inner side of the outer mitochondria membrane
On the outer side of the inner mitochondria membrane
On the inner side of the inner mitochondria membrane
Free in the matrix of the mitochondria
4
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
19. If electrons were removed from α-ketoglutarate and you could watch them move
down the electron transport system, the order of movement would be as follows:
A.
B.
C.
D.
E.
NADH, Complex I, CoQ, Complex III, Cytochrome C, Complex IV, H2O
NADH, Complex I, Complex II, CoQ, Cytochrome C, Complex IV, H2O
NADH, Complex II, CoQ, Cytochrome C, Complex III, Complex IV, H2O
NADH, Complex I, CoQ, Complex II, Cytochrome C, Complex III, H2O
NADH, Complex I, Complex II, Cytochrome C, Complex III, CoQ, Complex IV,
H2O
20. Which of the following statements does NOT help explain the chemiosmotic theory?
A. Protons move down a concentration gradient with negative free energy change
B. ADP and Pi combine to form ATP, this reaction has a positive change in free
energy
C. The inner mitochondria membrane is impermeable to protons
D. The only way protons can enter the mitochondria is through the ATP synthase
with the concomitant synthesis of ATP
E. The outside of the mitochondria is negative with respect to the matrix
21. A mitochondrion is producing ATP at a constant rate and, then, a chemical uncoupler
is added. Compared to before the uncoupler was added:
A.
B.
C.
D.
E.
Less heat would be produced
Less water would be produced
More NADH would be oxidized
More ATP would be produced
The proton gradient across the membrane would be increased
22. The cleavage of the high-energy bond of ATP into ADP and Pi is an example of what
type of reaction?
A.
B.
C.
D.
E.
Oxidation-reduction
Phosphorylation
Acetylation
Hydrolysis
Amination
23. Delta-G is negative, Delta-Go' is positive. Will the reaction occur spontaneously?
A. Yes
B. No
C. Not enough information to determine the answer
24. Which of the following is NOT an example in which ATP is utilized in the body for
work?
5
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
A.
B.
C.
D.
E.
Contraction of muscle
Entry of water into cells through specific pores
Phosphorylation of glucose by hexokinase
Maintenance of the Na+ and K+ concentration gradients
Formation of glycosidic bonds to make glycogen
25. The phosphorylation of glucose to glucose-6-phosphate has a Delta Go'of +3.3
kcal/mol. So why does the reaction occur in almost every cell of our body?
A.
B.
C.
D.
E.
Glucose becomes unstable intracellularly
Hexokinase is present
ATP hydrolysis
High concentration of glucose in the blood compared to cell
This reaction is coupled to another that has a much higher positive Delta Go
26. Which of the following statements regarding electron-accepting coenzymes is
INCORRECT?
A.
B.
C.
D.
FAD accepts electrons as the hydrogen atom
NADH is the reduced form of the coenzyme
FAD(H2) is synthesized from the vitamin riboflavin
The Delta Go' for the oxidation of NADH by the electron transport chain is
negative
E. The electrons donated to these coenzymes are subsequently removed by the
enzymes of the TCA cycle
27. Which of the following statements regarding the TCA cycle is CORRECT?
A. The rate-limiting step involves the enzyme malate dehydrogenase
B. For each acetyl CoA entering the cycle, two molecules of CO2 are produced
C. For each acetyl CoA entering the cycle, 24 high-energy phosphate bonds are
produced
D. The cycle will not function unless glutamate is present
E. The TCA cycle occurs in the rough endoplasmic reticulum of virtually every cell
in the body
28. Which of the following statements regarding the alpha-ketoglutarate dehydrogenase
complex is INCORRECT?
A.
B.
C.
D.
E.
One of its coenzymes - lipoic acid - comes from the vitamin B-carotene
It requires FAD as a coenzyme
Carbon dioxide is produced by this complex
One of its coenzymes - CoASH - comes from the vitamin pantothenate
It catalyzes the reaction converting a-ketoglutarate into succinyl CoA
6
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout
29. Which enzyme complex in the TCA cycle requires the cofactors thiamine
pyrophosphate, lipoic acid, CoA, FAD and NAD+?
A.
B.
C.
D.
E.
Citrate synthase
a-ketoglutarate dehydrogenase
Succiny-CoA synthetase (succinate thiokinase)
Malate dehydrogenase
Fumarase
30. Which of the following statements about the coenzyme FAD is INCORRECT?
A. It accepts single electrons
B. The TCA cycle enzyme that transfers electrons to FAD is found in the inner
mitochondrial membrane
C. It is very reactive in solution
D. It remains tightly bound to the holoenzyme
E. FADH2 is an important allosteric inhibitor of the TCA cycle
31. Which of the following statements about the TCA cycle is CORRECT?
A. Citrate is frequently used for gluconeogenesis in the liver
B. The production of oxaloacetate by pyruvate carboxylase is one of several
anaplerotic reactions for the TCA cycle
C. Succinyl CoA is used to create a neurotransmitter in the brain
D. Pyruvate dehydrogenase helps convert pyruvate into malate
E. Pyruvate carboxylase is only found in RBCs
32. Which of the following statements regarding the pyruvate dehydrogenase complex is
INCORRECT?
A.
B.
C.
D.
E.
When the complex is phosphorylated, it is inactive
Binding of pyruvate to the enzyme complex decreases the activity of the kinase
High [ADP] stimulates the conversion of pyruvate to acetyl CoA
The phosphatase which activates the complex is itself inhibited by Ca2+
The kinase associated with the pyruvate dehydrogenase complex is an enzyme
that adds phosphate groups
31. Which of the following statements regarding Complex II is INCORRECT?
A. This is one means by which the TCA cycle is linked to the electron-transport
chain
B. Succinate dehydrogenase is embedded in the inner mitochondrial membrane
C. Neither the single- or 2-electron forms of FAD dissociate from the enzyme
D. Complex II transfers its electrons directly to cytochrome c
7
Review Questions, Advanced Biochemistry,
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E. The transfer of electrons from FAD(2H) to the electron-transport chain results in
the synthesis of approximately 1.5 ATPs
32. Which of the following are in the correct sequence?
A.
B.
C.
D.
E.
Cytochrome Q; NADH dehydrogenase; Cytochrome c; Cytochrome oxidase
Complex I; Cytochrome c; Complex II; Cytochrome oxidase
NADH dehydrogenase; Cytochrome b-c1; Cytochrome c; Cytochrome oxidase
Succinate dehydrogenase; Coenzyme Q; Cytochrome oxidase; Cytochrome c
Complex I; Complex II; Coenzyme Q; Cytochrome oxidase
33. All of the following can act as "uncouplers" EXCEPT:
A.
B.
C.
D.
E.
Brown adipose tissue
Proton ionophores
Thermogenin (in infants)
Thyroid hormone
Cyanide
34.Assume standard biological conditions and that all the enzymes are present to catalyze
the reactions. Given the following data:
Glucose + Pi = glucose-6-P + H2O, ΔGo′ = +3.3 kcal/mol
ATP + H2O = Pi + ADP,
ΔGo′ = -7.0 kcal/mole
Calculate the ΔGo′ for the following reaction and determine whether the reaction is
spontaneous
Glucose + ATP --> Glucose-6-P + ADP
A.
B.
C.
D.
E.
–10.3 kcal/mol and spontaneous
+10.3 kcal/mol and not spontaneous
–3.7 kcal/mol and not spontaneous
+3.7 kcal/mol and not spontaneous
–3.7 kcal/mol and spontaneous
35. Which of the following is not a component of the Cori cycle:
A.
B.
C.
D.
E.
Aerobic glycolysis
Blood lactate
Gluconeogenesis
Blood glucose
Glycolysis in red blood cells
8
Review Questions, Advanced Biochemistry,
My best Wishes: Dr. Kamal E. M. Elkahlout