Exam 2 MC Question Bank Flashcards
(121 cards)
1
Q
Sequence the following events with regards to His12 and His119 working together to catalyze the RNAase A reaction.
A. His119 acts as a base by deprotonating a water molecule from the solvent to activate it for hydrolysis of the cyclic nucleotide intermediate
B. His12 acts a a base catalyst to remove a proton from the 2’-OH of the RNA phosphorous atom nearby
C. His12 acts as an acid and protonates the oxygen bond to the phosphorous atom
D. His119 acids as an acid catalyst and donates a proton to the leaving group, oxygen, to promote bond breakage
A
C
2
Q
What is the main product of glycogen degradation?
What is the main product of glycogen degradation?
A. Fructose-6-Phosphate
B. Glucose-1-Phosphate
C. Glucose-6-Phosphate
D. Fructose-1,6-biphosphate
E. Fructose-6-phosphate
A
B.
Admin comment: You may want to specific “initial product” or “product of initial steps” or something like that. Some might consider the mutase to be part of “glycogen degradation”
3
Q
Which of the following compounds does not capture the release of energy for use? A. H3CCOSCH3 B. Polysaccharides C. Some bullshit structure D. Reduced Coenzymes (NADH,FADH2,QH2
A
B.
4
Q
What is the primary function of Phosphoglucose Isomerase?
A. To convert F6P to FBP
B. To aid Triose Phosphate Isomerase to convert an aldose to a ketose.
C. To covert G6P to F6P
D. This is not an enzyme we have studied.
E. To help GAPDH help convert GAP to 1,3-BPG
A
C
5
Q
Competitive inhibitors do all of the following except: A. bind to the free enzyme B. resemble the substrate C. increase the KMapp D. bind to the enzyme complex E. Have a reversible KI
A
D
6
Q
Which is NOT true as to why glucose is stored as glycogen?
A. Glucose can be forced into different pathways while glycogen is not.
B. Glucose is more inert than Glycogen
C. Increase of Glucose concentration affects the osmolarity environment.
D. Glycogen is a polymer of glucose.
A
B
7
Q
Which implication of thermodynamics for metabolic pathways is true?
A. Metabolic pathways are reversible in the cell
B. Every metabolic pathway has two committed steps
C. Catabolic and anabolic pathways differ
D. All reactions in the metabolic pathway have a positive delta G
A
C
8
Q
Which of the following responses includes the appropriate enzyme and thermodynamic characteristic of the committed step in glycolysis?
A. Phosphofructokinase-1, irreversible
B. Hexokinase, reversible
C. Aldolase, irreversible
D. Triose Phosphate Isomerase, irreversible
E. Phosphoglycerate Kinase, reversible
A
A.
9
Q
What enzyme catalyzes the reaction of Fructose1-6-biphosphate to glyceraldehyde 3-phosphate + dihydroxyacetone phosphate? A. Hexokinase B. glucose-6-phosphate C. Phosphoglucomutase D. alodase E. pyruvate kinase
A
D
10
Q
You are trying to develop a drug to inhibit an enzyme by competitive inhibition. Based on experimentally the most effective inhibitors, what molecule should you strategize to model the structure of the drug to resemble, in order to have the most effective inhibition?
A. The reaction’s substrate
B. The reaction’s transition-state intermediate
C. The reaction’s product
D. A molecule that binds to the enzyme outside of the activation site that causes an allosteric conformation change
A
B (Comment says answer is A)
11
Q
Which of the following sugars can be used by hexokinase within muscle cells during glycolysis? A. Galactose B. Mannose C. Fructose D. Lactose E. Dextrose
A
C. Hexokinase in muscle cells can use fructose as a substrate (a substitution for glucose) during glycolysis. Fructose becomes phosphorylated by hexokinase to make fructose 6 phosphate, a good substrate for PFK 1. Fructose 6 phosphate will then be phosphorylated a second time to continue in the glycolysis process.
12
Q
The following is a Double Reciprocal Plot (intersect at y-axis; same Vmax, different KM) where an inhibitor is present and is not present in an enzyme. Which kind of inhibitor is present and why?
A. Uncompetitive Inhibitor, because Km increases with the inhibitor present and Vmax is not changed.
B. Competitive Inhibitor, because Km increases with the inhibitor present and Vmax is not changed.
C. Noncompetitive Inhibitor, because Km increases with the inhibitor present and Vmax is not changed.
D. Competitive Inhibitor, because Km decreases with the inhibitor present and Vmax is not changed.
E. Uncompetitive Inhibitor, because Km decreases with the inhibitor present and Vmax is not changed.
A
B
13
Q
An individual is resting on the couch and has a high amount of ATP available. Will glycolysis continue to occur if the person remains sedentary? Why or why not?
A. Yes, hexokinase will continue to bring in more glycogen to add to the ATP stores
B. Yes, pyruvate dehydrogenase is overly active in sedentary individuals
C. No, the high amounts of ATP will inhibit phosphofructokinase activity
D. No, the high amounts of ATP will inhibit glycogen synthase
E. Yes, ATP constantly disassociates on its own so it must constantly be replenished
A
C
14
Q
In Glycolysis there are ten steps and four of them use Kinases. Which four steps use Kinases and what ion do these Kinases require? A. 3, 6, 8, and 9; K+ B. 1, 3, 7, and 10; Mg2+ C. 3, 6, 8, and 9; Fe2+ D. 1, 3, 7, and 10; Ca2+ E. 3, 6, 8, and 9; Na+
A
B
15
Q
Which of the following is NOT a coenzyme? A. CoA B. Mg2+ C. NADH D. FADH2 E. NAD+
A
B
16
Q
In the catalytic mechanism of lysozyme, the unusual pKa of glutamate 35 allows it to act as a ________ by ________________.
A. Base catalyst; de-protonating the oxygen-1 atom that is part of the beta 1-4 linkage connecting the D and E rings
B. Acid catalyst; protonating the oxygen-1 atom that is part of the beta 1-4 linkage connecting the D and E rings
C. Both an acid and a base catalyst; protonating the oxygen-1 atom that is a part of the beta 1-4 linkage and later in the mechanism de-protonating the oxygen-1 atom to give the final product
D. None of the above
A
B
17
Q
Which of the following is true about the Pentose Phosphate Pathway?
I.The Pentose Phosphate Pathway supplies Ribose-5-phosphate to cells through the synthesis of Glucose-6-phosphate.
II.Synthesis of Ribose-5-Phosphate is required for metabolism of amino acids.
III.The Pentose Phosphate Pathway is reliant upon the availability of NADPH, and is inhibited by a lack of this molecule.
IV. The Pentose Phosphate Pathway occurs in tissues that synthesize fatty acids, such as the liver and adipose tissue.
V.Erythrocytes use the oxidized form of NADP+ as a result of this pathway to maintain reduced iron in hemoglobin.
A. I, II, III, V
B. I, III, IV
C. I, II, IV
D. I, III, V
E. All of the above
A
C
18
Q
Enzymes help reactions reach equilibrium more quickly by
A. increasing activation energy
B. keeping activation energy constant
C. enzymes have no control over activation energy
D. decreasing activation energy
E. none of the above
A
D
19
Q
Which of the following is true regarding enzymatic catalysis?
A. Enzymes have no effect on overall energy of activation and use structural changes to increase the rate of reaction
B. The decrease in stability during transient bond formation allows for decomposition of a molecule which increases the rate of reaction
C. Hydroxyl, sulfhydryl, amino, and imidazole are all important biological nucleophiles for metabolic reactions within the body
D. Metal ion catalysis involves the binding of 1st row transition state metals to the side chains of the enzyme to prevent binding to the active site
E. When binding sites with low specificity are used, correct positioning of reacting groups occurs, ultimately increasing degrees of freedom and allowing for easier degradation of enzyme-substrate complex
A
C
20
Q
An enzyme has a KM of 12mM in the absence of a competitive inhibitor and a KMapp of 18mM in the presence of 4mM of the inhibitor. Calculate KI. A. KI=10.25mM B. KI=8.00mM C. KI=14.10mM D. KI=16.00mM E. KI=7.75mM
A
B. KI is equal to [Inhibitor]/(a-1), where a= KMapp/KM. So, a= 18mM/12mM= 1.5. KI= 4mM/(1.5-1) = 8.00mM.
21
Q
This Lineweaver-Burk graph was produced by enzyme A (dotted line) and enzyme A + an inhibitor (solid line) (PARALLEL LINES). Which of the following statements is correct?
A. The ΔG of the inhibited reaction is higher that than of the uninhibited reaction. Adding more substrate would cause the effect of the inhibitor to lessen.
B. According to apparent Km values, the enzyme has a greater affinity for the substrate without the inhibitor present. The inhibitor used is uncompetitive.
C. Adding more substrate to the reaction would have no effect on the inhibitor’s activity. The inhibitor is binding to the same site as the substrate.
D. The y-intercept is equal to α’/Vmax where α’ is 1 when there is no inhibitor. The inhibitor is causing an allosteric change to the enzyme’s structure.
E. Because the inhibitor is noncompetitive, adding more substrate to the reaction would not
E have an effect on the inhibitor’s activity. The ΔG of the inhibited reaction is higher than that
of the uninhibited reaction.
A
D
22
Q
In what form is a Glucose derivative transferred to in order to recycle carbon atoms for further use in Glycolysis (not from the very beginning of Glycolysis)? A. G6P B. Glycogen C. RuBisCO D. Xu5P E. GAP
A
D
23
Q
Which of the following is true about the net glycolysis reaction? I. One molecule of glucose is consumed II. Four molecules of ATP are created III. Two molecules of NADH are created IV. Three molecules of pyruvate are produced A. III & IV B. II & IV C. I, II, & IV D. I & III E. II, III & IV
A
D
24
Q
Aldehyde dehydrogenase is an enzyme which oxidizes Acetaldehyde produced from the oxidation of ethanol. In many East Asian populations, a genetic mutation has resulted in a nearly inactive form of Aldehyde dehydrogenase. Compared to a normal enzyme, one would expect the inactive enzyme to have which of the following? A. Higher Km. Higher Kcat B. Higher Km. Lower Kcat C. Lower Km. Higher Kcat D. Lower Km. Lower Kcat
A
B
25
Which of the following steps are irreversible in glycolysis?
1. Fructose 6 phosphate to fructose 1,6 biphosphate 2. Glucose to Glucose 6 phosphate
3. Glucose 6 phosphate to fructose 6 phosphate
4. Phosphoenolpyruvate to pyruvate
A. 1, 2, 3
B. 1, 2
C. 1, 4
D. 3, 4
E. 1, 2, 4
E
26
```
Which of the following would serve to allosterically inhibit the rate of glycolysis?
A. Increased fructose
B. Decreased ATP
C. Increased glucose
D. Increased oxygen
E. Increased ATP
```
E
27
Which of the following are considered somewhat universal observations about metabolic pathways?
I. Catabolic and anabolic reactions cannot run completely in reverse
II. They tend to be irreversible in vivo
III. There are no committed steps for the pathways
IV. They have a committed step that ensures the substrate is moving in one overall direction
V. Reactions can always run completely in reverse
A. III & V
B. I, II, & IV
C. IV only
D. II & IV
E. I & V
B
28
Which of the following is true about the monosaccharides D-glucose and D-fructose?
A. For glucose, carbon 2 is oxidized to a ketone and carbon 1 on fructose is oxidized to an aldehyde
B. For glucose, carbon 1 is oxidized to a ketone and carbon 2 on fructose is oxidized to an aldehyde
C. For glucose, carbon 2 is oxidized to an aldehyde and carbon 1 on fructose is oxidized to a ketone
D. For glucose, carbon 1 is oxidized to an aldehyde and carbon 2 on fructose is oxidized to a ketone
E. Glucose is referred to as a ketose and fructose is referred to as an aldose
D
29
Does anaerobic glycolysis produce ATP faster than aerobic glycolysis? Why?
A. False, aerobic glycolysis is more thermodynamically favored, therefore it produces ATP at a faster rate
B. True, anaerobic glycolysis is more thermodynamically favored, therefore it produces ATP at a faster rate
C. False, aerobic glycolysis has high concentrations of reactants and products, therefore it produces ATP at a faster rate
D. True, anaerobic glycolysis produces ATP at a faster rate because anaerobic glycolysis occurs takes place in muscle tissue at a higher temperature
B? Outten wrote lots of comments on this one. Basically take this with a grain of salt.
30
```
Which of the following mechanisms of catalysis are exhibited in the catalytic mechanisms of Serine Proteases?
I. Acid-Base Catalysis
II. Covalent Catalysis
III. Metal Ion Catalysis
IV. Proximity Effect/Orientation
V. Transition State Stabilization
A. I, II & V
B. I & II
C. I, IV, & V
D. II, III & V
E. I, II & IV
```
A.
31
```
First molecule has OH in the trans configuration to CH2OH, second has OH in the cis configuration. The 2nd molecule is an example of:
A. Alpha-anomer
B. Epimer
C. Beta-anomer
D. Enantiomer
```
C.
| Admin Comment: The two molecules are also epimers of each other so that answer could arguably be correct.
32
In the lysozyme mechanism, which step produces a covalent intermediate?
A. Aspartate52 performing a nucleophilic attack on C1 of the oxonium ion transition state.
B. Glutamate35 performing a nucleophilic attack on C1 of the oxonium ion intermediate.
C. Aspartate52 protonating the O1 atom that is past of the beta 1,4- linkage connecting D/E rings.
D. Glutamate35 protonating the O1 atom that is past of the beta 1,4- linkage connecting D/E rings.
E. None of the above.
A
33
```
The interconversion of glycogen to glucose begins in the postabsorptive phase in order for the body to maintain its strict glucose levels in the blood, producing glucose-1-phosphate to be converted to glucose-6-phosphate. Likewise, upon the introduction of lactose, enzymes can degrade the disaccharide, producing a galactose molecule which can be used to produce glucose-1-phosphate as well. Which of the following serves as the intermediate of this pathway between galactose and glucose-1-phosphate, allowing it to inevitably be metabolized by glycolysis?
A. UDP-glucose
B. UDP-galactose
C. galactose-1-phosphate
D. glucose-1,6-bisphosphate
E. fructose-6-phosphate
```
C
34
```
Which step (and enzyme) of glycolysis is the irreversible, "committed" step of the pathway?
A. Step 3: Hexokinase
B. Step 10: Pyruvate Kinase
C. Step 1: Hexokinase
D. Step 1: Phosphofructokinase (PFK-1)
E. Step 3: Phosphofructokinase (PFK-1)
```
E
35
Which of the following is TRUE concerning enzymes and the effects of enzymes on a reaction:
I. Enzymes can decrease the overall Gibbs Free Energy of the reaction
II. Enzymes decrease the activation energy of the reaction
III. Enzymes have specificity and participate in a select few reactions
IV. Enzymes cannot be subjugated to regulation once it has begun acting in a metabolic pathway
A. I & IV
B. II & III
C. I, II, & III
D. I, III, & IV
B
36
In skin cells, which reaction would Ribulose-5-phosphate be most likely to undergo?
A. An epimerization reaction, generating Xylulose-5-phosphate
B. An isomerization reaction, generating Xylulose-5-phosphate
C. An epimerization reaction, generating Ribose-5-phosphate
D. An isomerization reaction, generating Ribose-5-phosphate
E. It would not undergo any of these reactions in a skin cell
D. Skin cells are rapidly dividing cells, so ribose-5-phosphate would be most likely to found in these cells since it can be used as a precursor for nucleotides. In order for ribulose- 5-phosphate to be turned into ribose-5-phosphate it must undergo an isomerization reaction. If it were to undergo epimerization it would end up as xylulose-5-phosphate.
37
Phosphofructokinase is a major control point in the glycolysis process. Which statement below is false regarding its structure/function?
A. PFK is a homo-tetrameric enzyme
B. ATP functions as both a substrate and an allosteric inhibitor of PFK
C. PFK-1 is the first metabolically irreversible step in glycolysis
D. PFK is found in both active (R) and inactive (T) states
C
38
Glycogen phosphorylase (GP) and glycogen synthase (GS) control glycogen metabolism and storage in liver and muscle cells. Mutations in these enzymes and similar enzymes can lead to all of the following conditions except:
A. Enlarged liver
B. Biliary Atresia
C. Hypoglycemia
D. Her's disease
E. None of the above, all are possible conditions
B
39
```
What alcohol, catalyzed by Alcohol Dehydrogenase, is converted to formaldehyde in the body, which can have detrimental effects to the optical nerve and in some cases cause fatalities?
A. Ethanol
B. Butanol
C. Methanol
D. Propanol
E. cyclohexanol
```
C
40
Which of these catalytic mechanisms is NOT utilized by Serine Proteases?
A. Covalent catalysis
B. Metal ion catalysis
C. Preferential binding to transition state
D. Acid/base catalysis
E. Electrostatic interactions
B
41
Glucose is the major metabolic fuel in the body and mammals maintain their own blood glucose levels.
How does the body respond to maintain blood glucose levels during fasting or starvation within the body?
A. Body first breaks down stored glycogen to release glucose
B. During phase 3-4, via gluconeogenesis the liver begins to synthesize new glucose from non- carbohydrate sources
C. The body can not maintain blood glucose levels during starvation or fasting
D. both A and B
E. none of the above
D
42
Glucose is the main sugar that is used to begin glycolysis. There are, however, other sugars that can be used by glycolysis to create the necessary products at different steps to keep glycolysis moving forward. The following sugars that can be used aside from glucose are: mannose, fructose, and galactose.
Which answer has the correct product that the sugars make in glycolysis and where the body gets them from?
A. Mannose (muscle): G6P, F6P
Fructose (liver, dietary polysaccharides): F6P Galactose (milk): GAP
B. Mannose (muscle): F6P
Fructose (liver, dietary polysaccharides): GAP, F6P Galactose (milk): G6P
C. Mannose (liver): G6P, F6P
Fructose (muscle): F6P
Galactose (dietary fats): GAP
D. Mannose(dietary polysaccharides): F6P
Fructose (liver, muscle): GAP, F6P
Galactose (milk): G6P
E. Mannose (dietary polysaccharides): GAP
Fructose (liver, muscle): F6P, GAP
Galactose (dietary fats): F6P
DMannose: derived from the dietary polysaccharides and can only be phosphorated by hexokinase at C6 following this reaction chain to generate F6P (that is used in glycolysis):
manose --hexokinase--> manose-6-phosephate ---phosohpmase isomerase--> fructose-6-phosphsate (F6P)
Fructose: extracted from the muscle and liver of the body. It can be directly phosphorylated by hexokinase (similarly to mannose as stated above) when derived from the muscle to make F6P. When fructose is used from the liver it is oxidized to make more GAP to be consumed in constant forward reaction with GAPDH
Galactose: extracted from milk; galactose is phosphorylated at the C1 end and a UDP is transferred from UDP-Glu to Galactose (makes UDP-Galactose). An epimerase then converts it to UDP-Glu and once the Glucose 1 phosphate is released it makes G6P which helps drive forward glycolysis.
43
Why is triose phosphate isomerase important in the process of glycolysis?
A. This enzyme converts a ketose into an aldose, and this aldose will only proceed through the rest of the pathway.
B. It is an enzyme that catalyzes an irreversible reaction, moving the glycolytic pathway forward instead of backwards.
C. It catalyzes the transfer of a phosphoryl group from ATP to glucose.
A
44
Match the following Lineweaver-Burke plots with the correct inhibitor description:
Graph 1: (PARALLEL LINES)
Graph 2: (INTERSECT AT Y-AXIS)
Graph 3: (INTERSECT TO THE LEFT OF Y-AXIS)
A. Graph 1 is Competitive inhibitor, Graph 2 is Uncompetitive inhibitor, and Graph 3 is Noncompetitive inhibitor.
B. Graph 1 is Noncompetitive inhibitor, Graph 2 is Uncompetitive inhibitor, and Graph 3 is Competitive inhibitor.
C. Graph 1 is Uncompetitive inhibitor, Graph 2 is Noncompetitive inhibitor, and Graph 3 is Competitive inhibitor.
D. Graph 1 is Uncompetitive inhibitor, Graph 2 is Competitive inhibitor, and Graph 3 is Noncompetitive inhibitor.
D
45
```
Which of the following inhibits binding of the substrate?
A. Mixed Inhibitor
B. Noncompetitive Inhibitor
C. Competitive Inhibitor
D. Uncompetitive Inhibitor
```
C
46
```
The enzyme pyruvate decarboxylase uses what as a cofactor during alcoholic fermentation?
A. Zinc
B. NADPH
C. Heme
D. Thiamine Pyrophosphate
E. Pyridoxal phosphate
```
D
47
```
Alpha-glucosidase is an enzyme found in the small intestine that breaks down starch and disaccharides to glucose. In traditional Indian medicine, the Cymbopogon martinii plant (CM) is used to treat diabetes mellitus due to its ability to inhibit this enzyme. These are the experimental results of a study of the activity of alpha-glucosidase at varying concentrations of maltose with different added concentrations of CM extract. Based on this Lineweaver- Burk plot, what type of inhibitor is CM? (INTERSECT TO THE LEFT OF Y-AXIS)
A. Competitive
B. Uncompetitive
C. Noncompetitive
D. None of these
E. Cannot be determined
```
C.
48
Which of the following correctly describes a major difference between NADPH and NADH?
A. NADPH is used mostly in catabolic reactions and NADH is used mostly in catabolic reactions
B. NADPH is used mostly in catabolic reactions while NADH is used mostly in anabolic reactions
C. NADPH is used mostly in anabolic reactions while NADH is used mostly in catabolic reactions
D. NADPH is used mostly in anabolic reactions while NADH is used mostly in anabolic reactions
C. NADH is known for its role in cellular respiration (catabolic), while NADPH is known for its role in photosynthesis (anabolic)
49
```
Based on the graph given, find the Vmax and Km values. (y-int=0.5, x-int=-2)
A. Vmax= -2 Km=-0.5
B. Vmax=2 Km=0.5
C. Vmax=0.5 Km=2
D. Vmax=0.25 Km=-0.25
E. Vmax=-2 Km=0.5
```
B
50
Which of these statements about metabolic pathways is false?
A. Metabolic pathways are irreversible
B. Every metabolic pathway has a first committed step
C. Catabolic and anabolic pathways differ
D. Metabolic pathways can proceed without the presence of ATP
D. But also, not every metabolic pathway has the first step as the committed step (i.e. glycolysis)
51
```
In the case of enzyme RNAase A, which of the following statements are true?
I. Histidine 12 is a base catalyst
II. Histidine 12 is an acid catalyst
III. Histidine 119 is a neutral catalyst
IV. Histidine 119 is an acid catalyst
A. Only I and IV
B. Only I, II, III
C. Only II, III
D. Only I, II, IV
E. Only III
```
D
52
What are the four kinases involved in glycolysis?
A. Hexokinase, Phosphofructokinase, Tyrosine kinase, Sphingosine kinase
B. Hexokinase, Pyruvate Kinase, mitogen-activated protein kinase, Cyclin dependent kinase
C. Pyruvate Kinase, Adenylate kinase, Tryosine kinase, Phosphatidylinositol kinases
D. Hexokinase, Phosphofructokinase, Phosphoglycerate Kinase, and Pyruvate Kinase
E. Phosphofructokinase, Phosphoglycerate Kinase, Adenylate kinase, Mitogen-activated protein kinase
D
53
```
The substrate used in the final step of glycolysis is
A. 1,3-Bisphosphoglycerate
B. Phosphoenolpyruvate
C. Pyruvate
D. Phosphoglycerate
E. Phosphofructokinase
```
B
54
What are the two primary functions of the Pentose Phosphate Pathway?
A. Synthesis of NADP+ for reproductive biosynthesis and the synthesis of R5P for the biosynthesis of ribonucleotides.
B. Synthesis of NADP+ for reproductive biosynthesis and the synthesis of G6P for the biosynthesis of ribonucleotides.
C. Synthesis of NADPH for reproductive biosynthesis and the synthesis of R5P for the biosynthesis of ribonucleotides.
D. Synthesis of NADPH for reproductive biosynthesis and the synthesis of G6P for the biosynthesis of ribonucleotides.
C
55
```
During the triose stage of glycolysis, how many ATP's are produced?
A. 1
B. 2
C. 3
D. 4
```
D
56
Which of the following is false regarding the enzyme lysozyme?
A. Lysozyme has a groove along one whole face of the protein where the substrate binds.
B. NAG residues bind in subsites A, C, and E.
C. When the six saccharide residues lay in the groove, the NAM sugar in sub-site B is distorted into a half-chair conformation.
D. While one residue of the polysaccharide is in the half-chair conformation, the other five residues bind in a normal chair conformation.
E. Lysozyme Glu 35 is a non-polar pocket, which raises the pKa of the carboxyl group on it's side chain.
C
57
```
If Phosphoenolpyruvate (PEP) were inhibited in the cell during glycolysis, what is the new net gain of ATP per 100 glucose molecules?
A. 2 ATP
B. 3 ATP
C. 1 ATP
D. 0 ATP
E. 4 ATP
```
D
58
Which of the following statements is TRUE regarding covalent catalysis?
A. Covalent bond formation helps to raise the energy of the transition state.
B. Covalent bond formation occurs when an electrophile on the protein attacks a nucleophilic group on the substrate.
C. The bond formed must be strong enough to not decompose during the formation of the final product.
D. Covalent catalysis occurs when there is a transient bond between the enzyme catalyst and the substrate.
E. The bond is formed when an acidic enzyme donates a hydrogen to a basic substrate.
D
59
```
Lysozyme is an enzyme that degrades which of the following?
A. oxonium ions
B. peptidoglycans
C. aspartate residues
D. amide groups
```
B
60
When is hexokinase used in glycolysis?
A. Converting Glucose to Glucose-6-Phosphate
B. Converting Fructose-6-Phosphate to DHAP
C. Converting 3-PhosophoGlycerate to 2-PhosphoGlycerate
D. Converting Fructose-1,6-BisPhosphate to GLAP
E. Converting 1,3-BisphosphoGlycerate to 3-PhosphoGlycerate
A
61
All of the following are properties of enzymes except...
A. they have less reaction specificity than most small molecule catalysts
B. they have few side reactions
C. they can enhance reactions by 14 fold
D. they function in mild conditions such as neutral pH and ambient pressure
E. they are essential for metabolic function
A
62
```
Histidine 12 and 119 of RNase A, a digestive enzyme, work together exemplifying which type of catalytic mechanism?
A. General Acid Catalysis
B. Metal Ion Catalysis
C. Covalent Catalysis
D. General Base Catalysis
E. Concerted Acid-Base Catalysis
```
E
63
Enzymes use multiple mechanism to catalyze reactions. In the proximity effect/orientation mechanism, which effect(s) by itself would cause the reaction rate to be accelerated?
A. Reducing the degrees of freedom
B. Decreasing the entropy of the reaction
C. Enhancing the concentration of substrate
D. Both A and C
E. All of the above would increase the rate of reaction
D
64
```
What designates the maximum rate of an enzyme-catalyzed reaction?
A. Vmax
B. Km
C. alpha
D. Vo
```
A
65
Which statement regarding phosphofructokinase-1 (PFK-1) is true?
A. ATP is both a substrate and allosteric activator while ADP is both a product and allosteric inhibitor.
B. ATP is both a product and allosteric activator while ADP is both a substrate and allosteric inhibitor.
C. ATP is both a substrate and allosteric inhibitor while ADP is both a product and allosteric activator.
D. ATP is both a product and allosteric inhibitor while ADP is both a product and allosteric activator.
E. AMP is the only allosteric activator of PFK-1.
C
66
```
Alpha-1-antitrypsin (A1AT) is a serine protease inhibitors that has been shown to reduce trypsin activity. When plotted on a Lineweaver-Burk plot, uninhibited trypsin activity is shown by the curve y=1.438x+12.69. Trypsin activity in the presence of A1AT is shown by the curve y=4.623x+16.32. Based on this information, what type of inhibitor is A1AT?
A. Competitive
B. Uncompetitive
C. Mixed
D. Not enough information to tell
```
C
67
Which of the following do not apply to the implications of thermodynamics for metabolic pathways?
A. Catabolic and anabolic pathways differ.
B. Every metabolic pathway has a first committed step.
C. Metabolic pathways are reversible.
D. Metabolic pathways are irreversible.
C
68
```
RNase A is a digestive enzyme used to degrade dietary RNA in the small intestine. What type of mechanism does RNase A use to catalyze this reaction?
A. acid-base catalysis
B. covalent catalysis
C. metal ion catalysis
D. proximity effect
E. transition state stabilization
```
A
69
```
Which of the following is the effect of a competitive inhibitor?
A. Increases KMapp
B. Decreases KMapp and vmaxapp
C. Decreases vmaxapp
D. May increase or decrease kMapp
E. No effect
```
A
70
```
Which of the following yields the most net ATP from glycolysis?
A. Fructose-1,6-bisphosphate
B. Glucose
C. Pyruvate
D. 2-phosphoglycerate
E. 3-phosphoglycerate
```
A
71
Which of the following best describes Km in a Lineweaver-Burk plot?
A. Km describes the maximum reaction velocity
B. Km is defined as the slope of the line
C. Km is the concentration of substrate
D. Km is the substrate concentration at which the reaction rate is half of Vmax
E. Km is the y-intercept on a Lineweaver-Burk plot, which is the substrate concentration at which the reaction rate is half of Vmax.
D
72
```
An enzyme catalyzed reaction has a KM of 1.5 mM and a Vmax of 8.0 nM*s-1. What is the reaction velocity when the substrate concentration is 0.25 mM?
A. Vo = 2.3 nM*s-1
B. Vo = 2.3 mM*s-1
C. Vo = 1.1 nM*s-1
D. Vo = 1.1 mM*s-1
```
C. Use the Michaelis-Menten Equation
73
```
Which enzymes can be used for BOTH glycolysis and gluconeogenesis?
I. glyceraldehyde-3-phosphate dehydrogenase
II. pyruvate carboxylase
III. pyruvate kinase
IV. phosphoglycerate kinase
V. enolase
A. I, II, and III
B. I, IV, and V
C. II, IV, and V
D. II and III
```
B
74
```
When 6 residues lay in the groove, NAM sugar in subsite ____ of the lysozyme is distorted into a half-chair conformation.
gluconeogenesis.
A. A
B. B
C. F
D. D
E. E
```
D
75
Which of the following is false about enzymes?
A. Lowers the activation energy
B. Increase the rate of the reaction
C. Affects the overall ΔG of the reaction
D. Does not alter the equilibrium constant
E. Are not changed or consumed in the reaction
C
76
Individuals with mutations in __________ have lower levels of NADPH and are sensitive to peroxide stress
A. glucose-6-phosphate dehydrogenase
B. GSSG
C. Acetyl CoA
A
77
```
Which of the following enzymes in glycolysis converts glucose-6-phosphate (G6P) to fructose-6-phosphate (F6P)?
A. Hexokinase
B. Aldolase
C. Phosphoglycerate mutase
D. Phosphoglucose isomerase
E. Phosphoglycerate Kinase
```
D
78
Why does the proximity effect enhance enzyme catalysis?
A. because it increases the "effective molarity" of substrates
B. by changing the conformation of the substrate's active site in the presence of the enzyme.
C. by decreasing entropy in an energetically favorable reaction.
D. it decreases size of the active site of the substrate.
E. it allows for the formation of transient bonds between the enzyme and substrate.
A
79
All of these properties of lysozymes are true EXCEPT:
A. Lysozymes degrade peptidoglycans
B. The lysozyme binding cleft accommodates 8 saccharide residues
C. Lysozymes hydrolyze the β 1,4 linkage between the NAG and NAM residues
D. Lysozymes are ellipsoid in shape
B
80
Which of the following is/are false?
I. Catabolic reactions are those where larger polymers are degraded to create smaller molecules and release energy
II. Metabolites are small molecule intermediates produced during the degradation and synthesis of biopolymers
III. Metabolic pathways tend to be reversible in vivo
IV. Diverse catabolic pathways converge on only a handful of key intermediates
A. III only
B. IV only
C. I and IV
D. II and III
E. All of the options are true
A
81
```
Which step of glycolysis is the "committed" step? Name the enzyme associated with it as well.
A. Step 1, Hexokinase
B. Step 4, Aldolase
C. Step 2, Phosphoglucose Isomerase
D. Step 3, phosphofructokinase-1
E. Step 10, pyruvate kinase
```
D
82
```
Which of the following is NOT used by enzymes to catalyze reactions:
I. acid - base catalysis
II. covalent catalysis
III. noncovalent catalysis IV. metal ion catalysis
V. proximity effect
VI. transition state stabilization
A. I, III, and V
B. only III
C. II and IV
D. only VI
E. II, IV, and VI
```
B
83
```
What type of reversible inhibition is depicted in this graph? (PARALLEL LINES)
A. Competitive Inhibiton
B. Noncompetitive (Mixed) Inhibition
C. Uncompetitive Inhibition
D. No inhibition is present.
```
C
84
Which of the following statements are NOT true about Km values?
A. Permits prediction of whether or not the rate of formation of product will be affected by the availability of substrate.
B. It is the concentration of substrates which permits the enzyme to achieve Vmax.
C. An enzyme with a high Km has a low affinity for its substrate, and requires a greater concentration of substrate to achieve Vmax.
D. An enzyme with a low Km is normally saturated with substrate and will act at a more or less constant rate, regardless of variations in the concentration of substrate within the physiological range.
B
85
```
Which of the following does the enzyme pyruvate decarboxylase use as a cofactor during alcohol fermentation?
A. Acetaldehyde
B. Thiamine Pyrophosphate
C. Alcohol Dehydrogenase
D. Glucose-6-dehydrogenase
E. Lactate Dehydrogenase
```
B
86
```
Which of the following is considered the major control point for Glycolysis?
A. Pyruvate kinase
B. Adenosine Triphosphate (ATP)
C. Adenosine Diphosphate (ADP)
D. Phosphofructokinase (PFK)
E. Glucose
```
D
87
```
Lithium is known to exert profound and selective psycho-pharmacological effects to help those with manic-depressive psychosis. There is increasing evidence that lithium exerts its therapeutic effects by uncompetitive inhibition on inositol monophosphatase. If the Vmax of the enzyme without an inhibitor bound is 10 μM/min and Km is 5 μM, which of the following describes how the Vmax and Km will change in the presence of lithium?
A. Km=5μM, Vmax= 5μM/min
B. Km=10μM, Vmax= 5μM/min
C. Km=1μM, Vmax= 5μM/min
D. Km=1μM, Vmax= 15μM/min
E. Km=10μM, Vmax= 10μM/min
```
C
88
What is the structure of glycogen?
A, Polymers of glucose monomers with mostly α-1-6 linkages, featuring branched points created by α-1-4 linkages.
B. Polymers of glucose monomers with alternating α-1-4 and α-1-6 linkages.
C. Polymers of glucose monomers with mostly α-1-4 linkages featuring branched points created by α-1-6 linkages.
D. Polymers of glucose monomers with α-1-3 linkages without any branched points.
C
89
What is the role of aldolase in glycolysis?
A. to cleave the six-Carbon fructose to generate two triose compounds (DHAP and GAP) that can enter a common degradative pathway in step 4 of glycolysis
B. to break down high levels of glucose in the liver after meals in step 1 of glycolysis
C. to convert a ketose (DHAP) into an aldose (GAP) so the compounds can proceed down the glycolytic pathway in step 5 of glycolysis
D. to remove a water molecules from C2 and C3 of 2-phosphoglycerate to create phosphoenolpyruvate in step 9 of glycolysis
E. to convert an aldose to a ketose in step 2 of glycolysis
A
90
A biochemist wants to examine two different substrates and their affinity to a certain enzyme. He measures the initial velocities of the reactions with differing substrate concentrations. He then plots these results on a graph and linearizes the data using the Lineweaver-Burk method. He determines that the maximum velocities are the same but they have differing Km values. Substrate A has a Km value of 0.03 and substrate B has a Km value of 0.1. For which substrate does the enzyme have a higher affinity?
A. Substrate A
B. Substrate B
C. They are the same because they have equal Vm values
D. There is not enough information to answer the question
A
91
Which enzyme is considered both an irreversible step and the committed step in glycolysis?
A. Hexokinase
B. Phosphofructokinase-1
C. Phosphoglycerate Kinase
D. Pyruvate Kinase
E. Glyceraldehyde-3-phosphate dehydrogenase
B
92
A student performs an inhibition experiment and measures the Vmax value and the Km value for the reaction with and without an inhibitor. The results are displayed in the following table.
Trial 1: No inhibitor.
Vmax=50, Km=10
Trial 2: With inhibitor.
Vmax=50, Km=30
Based on the preceding data, what type of inhibitor did the student add in Trial 2?
A. Irreversible inhibitor
B. Uncompetitive inhibitor
C. Competitive inhibitor
D. Noncompetitive inhibitor
E. There is not enough information to determine which inhibitor was used
C
93
You are studying the ability of a new drug to inhibit an enzyme. When investigating the enzyme kinetics, you notice that the substrate concentration must be higher to achieve half the maximum velocity in the presence of the drug. The value of the maximum velocity itself remains unchanged. What type of inhibition is caused by this new drug?
A. Uncompetitive
B. Competitive
C. Mixed/ Non-competitive
D. Not enough information to determine type of inhibition
B
94
Which is incorrect regarding glycolysis?
A. A net of two molecules of pyruvate and two molecules of NADH are produced.
B. Hexokinase catalyzes the transfer of a phosphoryl group from ATP to glucose.
C. Pyruvate kinase catalyzes the 2nd substrate-level phosphorylation reaction of glycolysis.
D. Phosphofructokinase is allosterically inhibited by high concentrations of fructose- 6-phosphate.
E. Phosphoenolpyruvate has a very high phosphoryl group transfer potential.
D
95
```
When an uncompetitive inhibitor is added to a reaction, which of the following effects occurs:
A. Km increases and Vmax increases
B. Km decreases and Vmax increases
C. Km increases and Vmax decreases
D. Km decreases and Vmax decreases
```
D
96
```
How many steps in the reaction of glycolysis involve a kinase? Also what steps are they in the process (in the way of numbering)?
A. six: 1,3,4,5,8,10
B. four: 1,3,7,10
C. five: 2,4,6,7,9
D. five: 1,3,6,7,10
E. four:1,2,3,7
```
B
97
```
Which of the following Isozymes of hexokinase is active at higher glucose levels (km~10^-2 M) in order to allow the liver to respond to large increases in blood glucose after eating a meal?
A. Hexokinase I
B. Hexokinase II
C. Hexokinase III
D. Hexokinase IV
```
D
98
```
The mechanism for catalyzing the hydrolysis of a peptide bond involves a catalytic serine residue in the enzyme active site. The enzymes share three important active site residues, called the catalytic triad. What are the names of these residues?
A. Tyrosine, Histidine, and Arginine
B. Serine, Histidine, and Aspartate
C. Serine, Phenylalanine, and Glutamate
D. Tyrosine, Tryptophan, and Aspartate
```
B
99
Which of the following is not a catalytic mechanism used by enzymes to increase the rate of reaction?
A. Proximity/Orientation Effects
B. Metal ion Catalysis
C. Ionic Catalysis
D. Acid-Base catalysis
E. Preferential binding of the transition state
C
100
```
What type of reversible inhibitor is this? (Lines intersect at y-axis)
A. Noncompetitive
B. Competitive
C. Mixed
D. Uncompetitive
```
B
101
Chronic Myeloid Leukemia (CML) consists of an overproduction of particular white blood cell types known as granulocytes. It is caused by a chromosomal translocation, which ultimately results in the expression of the BCR-ABL fusion protein (a mutated tyrosine kinase). Which of the following can be said about CML?
A. A CML patient's blood contains elevated levels of neutrophils, eosinophils, and monocytes.
B. The mutated gene in CML is contained in chromosome #9, also known as the Philadelphia Chromosome.
C. Imatinib treats CML by inhibiting the function of the BCR-ABL kinase.
D. Treatment can be discontinued once a CML patient's white blood cell count decreases.
E. The healthy ABL protein catalyzes hydrolysis reactions.
C
102
```
Overall what is the net production of ATP per glucose during glycolysis
A. 2 ATP
B. 4 ATP
C. 6 ATP
D. 3 ATP
E. None of the Above
```
A
103
Which of the following is false regarding alpha-D-glucopyranose?
A. Glucose forms a six-membered ring because its aldehyde is at carbon 1.
B. The –OH on the anomeric carbon is on the opposite side of the ring from the -CH2OH group on carbon 5.
C. In hexoses, carbon 5 is a chiral carbon that is used to designate the sugar as D or L stereoisomer.
D. The anomeric carbon is on carbon 2 in alpha-D-glucopyranose.
D
104
Which of the following is the type of glycosidic bond holding lactose together?
A. β-1,2
B. β-1,4
C. α-1,4
D. α-1,6
E. Lactose is monomeric and doesn't require any glycosidic bonds to hold its structure together.
B
105
Phosphofructokinase is considered the major control point within glycolysis due to its irreversible binding. Which of the following statements regarding PFK are false:
I. The T-state is considered the inactive active state within this step.
II. ATP acts as an inhibitor within PFK.
III. Fructose-2,6-bisphosphate and AMP are products of PFK.
IV. Allosteric regulators are utilized to affect reactions.
V. The addition of inhibitors results in a hyperbolic curve in a plot of Phosphofructokinase activity vs. the concentration of Fructose-6-phosphate in mM in a Lineweaver-Burk plot.
A. I, III, V
B. III and V
C. II and V
D. II, III, and IV
E. All statements are true
B
106
```
Which of the following is NOT one of the Metabolically Irreversible steps in glycolysis?
A. Step 1—glucose to G6P via HK
B. Step 3—F6P to FBP via PFK-1
C. Step 7—1,3-BPG to 3PG via PGK
D. Step 10—PEP to pyruvate via PK
```
C
107
Which of the following are true regarding uncompetitive inhibition as concentration of the inhibitor increases?
I. Vmax will increase
II. the Y-intercept value on the double reciprocal plot will increase
III. Km will be unchanged when Ki is equal to Ki prime
IV. The inhibitor will stop binding to the active site
V. Vmax will decrease
A. I, II, III
B. II, IV
C. II, V
D. I, II, IV
E. II
C
108
Which of the following is not an enzyme involved in the net reaction of glycolysis?
A. Glyceraldehyde 3-Phosphate Dehydrogenase
B. Methyl Transferase
C. Hexokinase
D. Triose Phosphate Isomerase
E. Aldolase
B
109
```
Which isozyme of Hexokinase is active at higher glucose levels and allows the liver to respond to large increases in blood glucoses that occur after meals?
A. Hexokinase I
B. Phosphoglucose
C. Isomerase Aldolase
D. Glucokinase
E. Triose Phosphate Isomerase
```
D
110
```
What mode of inhibition is displayed by this graph? (PARALLEL LINES)
A. No inhibition is shown.
B. Competitive
C. Noncompetitive
D. Uncompetitive
E. Mixed
```
D
111
```
Out of the 10 steps in the Glycolytic Pathway, which step catalyzes sub-level phosphorylation and is also irreversible?
A. Step 2: Phosphoglucose Isomerase
B. Step 3: Phosphofructokinase-1
C. Step 7: Phosphoglycerate Kinase
D. Step 10: Pyruvate Kinase
```
D
112
```
When consuming a meal, which of the following hexokinases allow the liver to respond to the large increase in blood glucose levels that comes from your food?
A. Hexokinase I
B. Hexokinase II
C. Hexokinase III
D. Hexokinase IV
E. Hexokinases I, II, and III
```
D
113
```
What is responsible for enzymatic activity in creatine kinase?
A. Positively charged amino acids
B. Negatively charged amino acids
C. Neutrally charged amino acids
D. Alpha carbon
E. Amine group
```
B
114
Which of the following is FALSE in regards to serine proteases:
A. The catalytic triad of serine proteases consists of Ser, His, and Asn.
B. Serine proteases include trypsin, chymotrypsin, and elastase.
C. Serine proteases hydrolyze the peptide bonds of polypeptide chains.
D. Serine proteases consist of enzymes necessary for digestion, as well as certain enzymes involved in the activation of the blood clotting cascade.
A
115
```
Which of the following is true about Alcohol Dehydrogenase? Select all that apply.
I. it converts ethanol to acecaldehyde
II. it has seven different isozymes
III. it converts methanol to formaldehyde
IV. it has high substrate specificity
A. I, II, III.
B. I, III, IV.
C. I and III only.
D. III and IV only.
E. all are true.
```
C
116
Which of the following is a correct statement?
A. A small Km means the enzyme has a low affinity for the substrate
B. A small Kd means the enzyme has a low affinity for the substrate
C. A large Km means the enzyme has a low affinity for the substrate
D. A high Vmax means the enzyme has a low affinity for the substrate
E. A low Vmax means the enzyme has a low affinity for the substrate
C
117
```
In lysozyme, Glutamate 35 is in a nonpolar pocket that raises the pKa of the carboxyl group, meaning the side chain is still protonated at unusually high pH. In the degradation of peptidoglycans, Glutamate 35 acts as:
A. an oxidoreductase
B. an acid-base catalyst
C. a covalent catalyst
D. a metal ion catalyst
E. a lyase
```
B
118
```
Inhibitors can bind to enzymes to block the reaction it carries out? Which type of inhibitor binds only to the free enzyme and not to the ES complex?
A. Noncompetitive Inhibitor
B. Uncompetitive Inhibitor
C. Competitive Inhibitor
D. A and B
E. A and C
```
C
119
```
What type of inhibition blocks the substrate from binding to the active site of the enzyme?
A. Noncompetitive Inhibition
B. Uncompetitive Inhibition
C. Suicide Inhibition
D. Production Inhibition
E. Competitive Inhibition
```
E
120
Which of the following is false regarding uncompetitive inhibitors?
A. Uncompetitive inhibitors bind and inhibit the ES complex but not the free enzyme.
B. Inhibition can be overcome by adding more substrate.
C. Decreases Km and Vmax values of the reaction.
D. Uncompetitive inhibition analyzed via the double reciprocal Lineweaver-Burk plot, the lines for data collected at different inhibitor concentrations will be parallel to each other.
B
121
Which of the following statements is false regarding the anomeric carbon of glucose?
A. The anomeric carbon is a chiral carbon in ring structures
B. The anomeric carbon was originally the aldehyde carbon number 1 of the linear form
C. The anomeric carbon can adopt an α or β configuration
D. The anomeric carbon is the least oxidized carbon of a cyclized monosaccharide
E. All of the above are true statements
D
