3rd LE Flashcards
True of Myokinase:
1. Catalyzes the irreversible transfer of phosphate groups from ADP
to ATP. X
2. Promotes catabolic reactions in the presence of increased AMP
concentration.
3. The enzyme is present only in muscle cells. X
4. Allows AMP to be rephosphorylated to ADP.
A. Statements 2 & 4 are correct.
B. All statements are correct.
C. Statements 1 & 3 are correct.
D. Statements 1, 2 & 3 are correct.
A. Statements 2 & 4 are correct.
Myokinase:
2. Promotes catabolic reactions in the presence of increased AMP
concentration.
4. Allows AMP to be rephosphorylated to ADP.
Enumerate the 3 major sources of energy conservation or energy
capture in the cell.
THE CITRIC ACID CYCLE, GLYCOLYSIS, OXIDATIVE PHOSPHORYLATION
Which of the following compounds have high group transfer
potential?
1. Carbamoyl phosphate
2. 1,3-Bisphosphoglycerate
3. Creatine phosphate
4. Pyrophosphate
A. All statements are correct.
B. Statements 2 & 4 are correct.
C. Statements 1 & 3 are correct.
D. Statements 1, 2 & 3 are correct.
D. Statements 1, 2 & 3 are correct.
- Carbamoyl phosphate
- 1,3-Bisphosphoglycerate
- Creatine phosphate
Metalloflavoproteins are a group of enzymes containing
flavoproteins and a metal ion. Which of these enzymes contain
molybdenum as the metal cofactor?
1. Xanthine oxidase
2. Pyruvate dehydrogenase
3. Aldehyde dehydrogenase
4. Amino Acid oxidase
A. All statements are correct.
B. Statements 1, 2 & 3 are correct.
C. Statements 1 & 3 are correct.
D. Statements 2 & 4 are correct.
C. Statements 1 & 3 are correct.
- Xanthine oxidase - molybdenum containing enzymes
- Aldehyde dehydrogenase - molybdenum & non-heme protein
True of superoxide free radicals.
1. Most important and widespread form under physiologic pH.
2. Can reduce iron-complexes.
3. Are products of normal cellular metabolism especially in the
mitochondria.
4. Superoxide dismutase catalyzes the reaction of superoxide
radicals to hydrogen peroxide and water
A. All statements are correct.
B. Statements 1, 2 & 3 are correct.
C. Statements 2 & 4 are correct.
D. Statements 1 & 3 are correct.
A. All statements are correct.
- Which of the following sites in the electron transport chain are
the likely sources of endogenous radical species?
A. Complex I
B. Complex III
C. Complex IV
D. Complex II
C. Complex IV
The drug Oligomycin significantly reduces the flow of electrons in
the electron transport chain in which of the following complexes?
A. Complex I, III & IV
B. Complex I, II & III
C. Complex I & III
D. Complex II & IV
A. Complex I, III & IV
Oligomycin completely blocks oxidation and phosphorylation by blocking the flow of protons through ATP synthase (Complex V)
In the ATP production, which of the following subunits in the
enzyme complex takes up phosphates consequently forming ATP?
A. Sigma
B. Gamma
C. Beta
D. Alpha
C. Beta
Which of the following is the most important energy shuttle
system found in myofibrils.
1. Glycerophosphate shuttle
2. Malate shuttle
3. Aspartate shuttle
4. Creatine phosphate shuttle
A. Statements 2 & 4 are correct.
B. Statement 4 is correct.
C. Statements 1, 2 & 3 are correct.
D. Statements 1 & 3 are correct.
B. Statement 4 is correct
MELAS (mitochondrial encephalopathy, lactic acidosis and
stroke), a rare genetic disorder affecting the enzymes of which of
the following complexes?
1. Complex III
2. Complex I
3. Complex II
4. Complex IV
A. Statements 2 & 4 are correct.
B. Statement 4 is correct.
C. Statements 1, 2 & 3 are correct.
D. Statements 1 & 3 are correct.
A. Statements 2 & 4 are correct.
- Complex I
- Complex IV
MELAS is inherited condition due to NADH-Q reductase(COMPLEX I) or cytochrome oxidase
(COMPLEX IV)
Which of the following enzymes are found in the mitochondrial
matrix?
1. Citric Acid Cycle enzymes
2. Pyruvate dehydrogenase
3. Fatty acid Beta-oxidation
4. Creatine kinase
A. Statements 2 & 4 are correct.
B. All statements are correct.
C. Statements 1, 2 & 3 are correct.
D. Statements 1 & 3 are correct.
C. Statements 1, 2 & 3 are correct
- Citric Acid Cycle enzymes
- Pyruvate dehydrogenase
- Fatty acid Beta-oxidation
Citric acid cycle enzymes including pyruvate dehydrogenase and B-oxidation enzymes are
found in the mitochondrial matrix
Creatine kinase is found in intermembrane space (together with adenylyl kinase)
Which of the following substances inhibits the Cytochrome P450
hydroxylase cycle.
1. Carboxin
2. Cyanide
3. Hydrogen sulfide
4. Carbon Monoxide
A. Statement 4 is correct.
B. Statements 1, 2 & 3 are correct.
C. Statements 1 & 3 are correct.
D. Statements 2 & 4 are correct.
A. Statement 4 is correct.
- Carbon Monoxide
In the general laws of thermodynamics, what is the most likely
result when delta G is positive?
1. Reaction is complete and is essentially irreversible.
2. Reaction proceeds when there is a net gain of energy.
3. Reaction proceeds spontaneously with a loss of energy.
4. Reaction may least likely occur or not occur at all.
A. Statements 1, 2 & 3 are correct.
B. Statements 1 & 3 are correct.
C. Statements 2 & 4 are correct.
D. Statement 4 is correct.
C. Statements 2 & 4 are correct.
- Reaction proceeds when there is a net gain of energy
- Reaction may least likely occur or not occur at all.
This enzyme is considered a specialized Nucleoside
Monophosphate kinase.
ADENYLYL KINASE or MYOKINASE
nucleoside monophosphate (NMP) kinases catalyze the formation of NDP from the
corresponding monophosphates.
Thus, Adenylyl kinase is a specialized NMP kinase.
This is the form of hemoglobin protein that contains ferric iron
(Fe3+) in the heme prosthetic groups due to oxidation.
A. myoglobin
B. oxyhemoglobin
C. deoxyhemoglobin
D. methemoglobin
D. methemoglobin
In methemoglobinemia, the heme iron is ferric rather than ferrous(metheme), rendering
methemoglobin unable to bind or transport O2.
Which of the following briefly describes myoglobin?
a. low affinity to bind to oxygen
b. higher molecular weight
c. lacks quaternary structure
d. tightly binds to oxygen
d. tightly binds to oxygen
Myoglobin - reservoir of oxygen; tightly binds to O2 more than hemoglobin
Why does the glycolytic pathway continue in the direction of glucose
catabolism?
A. Glycolysis occurs in either direction
B. High levels of ATP keep the pathway going in a forward direction
C. There are essentially three irreversible reactions that act as the
driving force for the pathway
D. The enzymes of glvcolvsis only function in one direction
C. There are essentially three irreversible reactions that act as the
driving force for the pathway
For every one molecule of sugar glucose which is oxidized, __ molecules of
pyruvic acid are produced.
A. 4
B. 3
C. 2
D. 1
C. 2
Glucose + 2NAD + 2ATP + 2ADP + 2P –> 2Pyruvate + 2NADH + 4ATP + 4ADP
In the glycogen synthase reaction, the precursor to glycogen is
A. UTP-glucose
B. glucose-1-P
C. UDP-glucose
D. glucose-6-P
C. UDP-glucose
Glycogenin catalyzes the transfer of a further seven glucose residues from UDPGlc, in
1 → 4 linkage, to form a glycogen primer that is the substrate for glycogen synthase.
The active form of glycogen phosphorylase is phosphorylated, while the
dephosphorylation of which active form occurs?
A. Glycogen hydrolase
B. Glycogen semisynthesis
C. Glycogen dehydrogenase
D. Glycogen synthase
D. Glycogen synthase
The Activities of Glycogen Synthase & Phosphorylase Are Reciprocally Regulated
- Active glycogen synthase a is dephosphorylated and inactive glycogen
synthase b is phosphorylated.
Which of the following is not true of glycolysis?
A. ADP is phosphorylated to ATP via substrate level phosphorylation
B. The pathway oxidises two moles of NAD- to NAD+ for each mole of
glucose that enters - NAD+ -> NADH
C. The pathway does not require oxygen
D. The pathway requires two moles of ATP to get started catabolizing
each mole of glucose
B. The pathway oxidises two moles of NAD- to NAD+ for each mole of
glucose that enters
its - NAD+ -> NADH
During glycolysis, the major energy-generating step involves
A. Phosphoglycerate kinase
B. Phosphofructokinase
C. Glyceraldehyde-3-dehydrogenase
D. Pyruvate kinase
C. Glyceraldehyde-3-dehydrogenase
Which of the following regulates glycolysis steps?
A. All are correct
B. Phosphofructokinase
C. Pyruvate Kinase
D. Hexose kinase
A. All are correct
Glycogen has:
A. ɑ-1,4 linkage
B. ɑ-1,6 linkages
C. ɑ-1,4 and ß-1,6 linkage
D. ɑ-1,4 and ɑ-1,6 linkage
D. ɑ-1,4 and ɑ-1,6 linkage
What is the other name of glycolysis?
A. TCA pathway
B. HMS pathway
C. EMP pathway
D. None are correct
Embden-Meyerhof-Parnas (EMP) pathway
Which of the following process occurs in glycolysis
A. Reduction
B. Fixation
C. Hydrogenation
D. Oxidation
D. Oxidation
How much ATP is/are used in glycolysis or For complete phosphorylation of a
glucose molecule how many ATP molecules are required?
A. 4
B. 6
C. 8
D. 2
D. 2
Which one of the following is the first step of glycolysis?
A. Dehydrogenation of glucose
B. Phosphorylation of glucose
C. Breakdown of glucose
D. Conversion of glucose into fructose
B. Phosphorylation of glucose
In the pentose phosphate pathway, the major products are:
A. Ribulose and NADH
B. Ribulose and NADPH
C. Ribulose and ATP
D. Ribulose and NAD+
B. Ribulose and NADPH
What is the first reaction of the pentose phosphate pathway?
A. Reduction of ketopentose ribulose 5-phosphate to 6-
phosphogluconate
B. Oxidation of glucose 6-phosphate to 6-phosphoglucono-δ-lactone
C. Oxidation of 6-phosphogluconate to ketopentose ribulose 5-
phosphate
D. Reduction of 6-phospho glucono-δ-lactone to glucose 6-phosphate
B. Oxidation of glucose 6-phosphate to 6-phosphoglucono-δ-lactone
Which of the following statements is correct about oxidative pentose
phosphate pathway?
A. It oxidizes NADPH to NADP+
B. Glucose 6-phosphatase catalyzes the rate limiting reaction of the
pathway
C. The pathway supplies ribose 5-phosphate and NADPH in the
quantities the cell requires
D. It generates NADH
C. The pathway supplies ribose 5-phosphate and NADPH in the
quantities the cell requires
Which one out of the following enzymes acts in the pentose phosphate
pathway?
A. Pyruvate Kinase
B. Glycogen phosphatase
C. 6-phosphogluconate dehydrogenase
D. Aldolase
C. 6-phosphogluconate dehydrogenase