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All questions of Glycolysis, Gluconeogenesis & Pentose Phosphate Pathway and Principle of Metabolic Regulation (BIO, BC) for MCAT Exam
What is the significance of substrate-level phosphorylation in glycolysis?- a)It produces ATP without the need for oxygen.
- b)It reduces NAD+ to NADH.
- c)It generates glucose from pyruvate.
- d)It involves the electron transport chain.
Correct answer is option 'A'. Can you explain this answer?
What is the significance of substrate-level phosphorylation in glycolysis?
a)
It produces ATP without the need for oxygen.
b)
It reduces NAD+ to NADH.
c)
It generates glucose from pyruvate.
d)
It involves the electron transport chain.
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Orion Classes answered |
Substrate-level phosphorylation in glycolysis allows for the direct generation of ATP from ADP using high-energy intermediates, independent of oxygen.
Which enzyme catalyzes the final step of glycolysis, converting phosphoenolpyruvate to pyruvate?- a)Phosphoglycerate kinase
- b)Pyruvate kinase
- c)Hexokinase
- d)Aldolase
Correct answer is option 'B'. Can you explain this answer?
Which enzyme catalyzes the final step of glycolysis, converting phosphoenolpyruvate to pyruvate?
a)
Phosphoglycerate kinase
b)
Pyruvate kinase
c)
Hexokinase
d)
Aldolase
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Emma Smith answered |
Enzyme in Glycolysis
In glycolysis, the final step involves the conversion of phosphoenolpyruvate (PEP) to pyruvate, and this reaction is catalyzed by the enzyme pyruvate kinase.
Role of Pyruvate Kinase
- Catalytic Function: Pyruvate kinase facilitates the transfer of a phosphate group from PEP to ADP, resulting in the formation of ATP and pyruvate.
- Irreversible Reaction: This step is considered irreversible and is a key regulatory point in glycolysis.
Significance of the Reaction
- Energy Production: The conversion of PEP to pyruvate is crucial because it generates ATP, providing energy for cellular processes.
- Metabolic Pathway Transition: Pyruvate serves as a vital intermediate that can enter the citric acid cycle or be converted into lactate under anaerobic conditions.
Comparison with Other Enzymes
- Phosphoglycerate Kinase: This enzyme acts earlier in glycolysis, converting 1,3-bisphosphoglycerate to 3-phosphoglycerate, also generating ATP but not at the final step.
- Hexokinase: This enzyme catalyzes the first step of glycolysis, converting glucose to glucose-6-phosphate, which is far from the final step.
- Aldolase: This enzyme is involved in splitting fructose-1,6-bisphosphate into two three-carbon sugars but does not participate in the final conversion to pyruvate.
Conclusion
In summary, pyruvate kinase is essential for the final step of glycolysis, converting phosphoenolpyruvate to pyruvate while producing ATP, making it a key enzyme in cellular metabolism.
In glycolysis, the final step involves the conversion of phosphoenolpyruvate (PEP) to pyruvate, and this reaction is catalyzed by the enzyme pyruvate kinase.
Role of Pyruvate Kinase
- Catalytic Function: Pyruvate kinase facilitates the transfer of a phosphate group from PEP to ADP, resulting in the formation of ATP and pyruvate.
- Irreversible Reaction: This step is considered irreversible and is a key regulatory point in glycolysis.
Significance of the Reaction
- Energy Production: The conversion of PEP to pyruvate is crucial because it generates ATP, providing energy for cellular processes.
- Metabolic Pathway Transition: Pyruvate serves as a vital intermediate that can enter the citric acid cycle or be converted into lactate under anaerobic conditions.
Comparison with Other Enzymes
- Phosphoglycerate Kinase: This enzyme acts earlier in glycolysis, converting 1,3-bisphosphoglycerate to 3-phosphoglycerate, also generating ATP but not at the final step.
- Hexokinase: This enzyme catalyzes the first step of glycolysis, converting glucose to glucose-6-phosphate, which is far from the final step.
- Aldolase: This enzyme is involved in splitting fructose-1,6-bisphosphate into two three-carbon sugars but does not participate in the final conversion to pyruvate.
Conclusion
In summary, pyruvate kinase is essential for the final step of glycolysis, converting phosphoenolpyruvate to pyruvate while producing ATP, making it a key enzyme in cellular metabolism.
In which part of the cell does glycolysis take place?- a)Nucleus
- b)Mitochondria
- c)Cytosol
- d)Ribosomes
Correct answer is option 'C'. Can you explain this answer?
In which part of the cell does glycolysis take place?
a)
Nucleus
b)
Mitochondria
c)
Cytosol
d)
Ribosomes
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Orion Classes answered |
Glycolysis occurs in the cytosol, where the enzymes necessary for the pathway are located, facilitating the breakdown of glucose.
What is the primary function of carbohydrates in metabolism?- a)To provide structural support to cells.
- b)To act as a major source of energy for living cells.
- c)To store genetic information.
- d)To facilitate enzymatic reactions.
Correct answer is option 'B'. Can you explain this answer?
What is the primary function of carbohydrates in metabolism?
a)
To provide structural support to cells.
b)
To act as a major source of energy for living cells.
c)
To store genetic information.
d)
To facilitate enzymatic reactions.
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Orion Classes answered |
The main role of carbohydrates in metabolism is to serve as a major source of energy for living cells. They are broken down to release energy, which is essential for various metabolic processes.
What is the end product of glycolysis under anaerobic conditions?- a)Acetyl-CoA
- b)Pyruvate
- c)Lactate
- d)Alcohol
Correct answer is option 'C'. Can you explain this answer?
What is the end product of glycolysis under anaerobic conditions?
a)
Acetyl-CoA
b)
Pyruvate
c)
Lactate
d)
Alcohol
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Orion Classes answered |
Under anaerobic conditions, the end product of glycolysis is lactate, formed when pyruvate is reduced to regenerate NAD+.
Which enzyme catalyzes the conversion of glucose to glucose 6-phosphate?- a)Phosphofructokinase
- b)Hexokinase
- c)Pyruvate kinase
- d)Aldolase
Correct answer is option 'B'. Can you explain this answer?
Which enzyme catalyzes the conversion of glucose to glucose 6-phosphate?
a)
Phosphofructokinase
b)
Hexokinase
c)
Pyruvate kinase
d)
Aldolase
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|
Orion Classes answered |
Hexokinase catalyzes the phosphorylation of glucose to form glucose 6-phosphate, a key regulatory step in glycolysis.
Which reaction is catalyzed by phosphofructokinase in glycolysis?- a)Conversion of glucose to glucose 6-phosphate.
- b)Conversion of fructose 6-phosphate to fructose 1,6-bisphosphate.
- c)Conversion of pyruvate to lactate.
- d)Conversion of glyceraldehyde 3-phosphate to pyruvate.
Correct answer is option 'B'. Can you explain this answer?
Which reaction is catalyzed by phosphofructokinase in glycolysis?
a)
Conversion of glucose to glucose 6-phosphate.
b)
Conversion of fructose 6-phosphate to fructose 1,6-bisphosphate.
c)
Conversion of pyruvate to lactate.
d)
Conversion of glyceraldehyde 3-phosphate to pyruvate.
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Orion Classes answered |
Phosphofructokinase catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, and this step is crucial as it is a major regulatory point in glycolysis.
What happens to pyruvate in anaerobic glycolysis?- a)It is converted into acetyl-CoA.
- b)It enters the Krebs cycle.
- c)It is converted into lactate.
- d)It is oxidized to CO2 and H2O.
Correct answer is option 'C'. Can you explain this answer?
What happens to pyruvate in anaerobic glycolysis?
a)
It is converted into acetyl-CoA.
b)
It enters the Krebs cycle.
c)
It is converted into lactate.
d)
It is oxidized to CO2 and H2O.
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Orion Classes answered |
In anaerobic glycolysis, pyruvate is converted into lactate to regenerate NAD+, allowing glycolysis to continue in the absence of oxygen.
How many ATP molecules are produced from one molecule of glucose during glycolysis under aerobic conditions?- a)2 ATP
- b)4 ATP
- c)6 ATP
- d)8 ATP
Correct answer is option 'D'. Can you explain this answer?
How many ATP molecules are produced from one molecule of glucose during glycolysis under aerobic conditions?
a)
2 ATP
b)
4 ATP
c)
6 ATP
d)
8 ATP
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Orion Classes answered |
Under aerobic conditions, a total of 8 ATP can be generated from one molecule of glucose during glycolysis, including those produced from NADH that enters the electron transport chain.
What is glycolysis?- a)A pathway that converts glucose into fatty acids.
- b)A series of reactions that convert glucose into pyruvate.
- c)A process that synthesizes glucose from pyruvate.
- d)A method of storing glucose in the liver.
Correct answer is option 'B'. Can you explain this answer?
What is glycolysis?
a)
A pathway that converts glucose into fatty acids.
b)
A series of reactions that convert glucose into pyruvate.
c)
A process that synthesizes glucose from pyruvate.
d)
A method of storing glucose in the liver.
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Orion Classes answered |
Glycolysis is a sequence of 10 enzyme-catalyzed reactions that convert glucose into pyruvate while producing ATP, making it a fundamental metabolic pathway.
Which three monosaccharides are primarily produced during digestion?- a)Glucose, sucrose, and starch.
- b)Glucose, fructose, and galactose.
- c)Fructose, lactose, and maltose.
- d)Galactose, glucose, and ribose.
Correct answer is option 'B'. Can you explain this answer?
Which three monosaccharides are primarily produced during digestion?
a)
Glucose, sucrose, and starch.
b)
Glucose, fructose, and galactose.
c)
Fructose, lactose, and maltose.
d)
Galactose, glucose, and ribose.
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Orion Classes answered |
The three principal monosaccharides resulting from digestion are glucose, fructose, and galactose, which are crucial for energy production.
In the context of glycolysis, what does the term 'committed step' refer to?- a)The first reaction in glycolysis.
- b)The phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate.
- c)The conversion of glucose to glucose 6-phosphate.
- d)The final conversion of pyruvate to lactate.
Correct answer is option 'B'. Can you explain this answer?
In the context of glycolysis, what does the term 'committed step' refer to?
a)
The first reaction in glycolysis.
b)
The phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate.
c)
The conversion of glucose to glucose 6-phosphate.
d)
The final conversion of pyruvate to lactate.
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Orion Classes answered |
The committed step in glycolysis refers to the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate, which commits the substrate to continue through the glycolytic pathway.
What is the primary difference between aerobic and anaerobic glycolysis?- a)Aerobic glycolysis produces more ATP.
- b)Aerobic glycolysis occurs in the cytosol, while anaerobic occurs in mitochondria.
- c)Aerobic glycolysis does not produce NADH.
- d)Aerobic glycolysis produces lactate, while anaerobic produces pyruvate.
Correct answer is option 'A'. Can you explain this answer?
What is the primary difference between aerobic and anaerobic glycolysis?
a)
Aerobic glycolysis produces more ATP.
b)
Aerobic glycolysis occurs in the cytosol, while anaerobic occurs in mitochondria.
c)
Aerobic glycolysis does not produce NADH.
d)
Aerobic glycolysis produces lactate, while anaerobic produces pyruvate.
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Orion Classes answered |
Aerobic glycolysis yields more ATP compared to anaerobic glycolysis because it allows for the complete oxidation of glucose through the Krebs cycle and oxidative phosphorylation.
What is the role of NAD+ in glycolysis?- a)To donate electrons for ATP synthesis.
- b)To act as an allosteric inhibitor.
- c)To serve as a substrate for the enzymes.
- d)To accept electrons and become NADH.
Correct answer is option 'D'. Can you explain this answer?
What is the role of NAD+ in glycolysis?
a)
To donate electrons for ATP synthesis.
b)
To act as an allosteric inhibitor.
c)
To serve as a substrate for the enzymes.
d)
To accept electrons and become NADH.
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Orion Classes answered |
NAD+ acts as an electron acceptor in glycolysis, getting reduced to NADH during the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.
Which of the following is an allosteric inhibitor of phosphofructokinase?- a)Fructose 1,6-bisphosphate
- b)ADP
- c)ATP
- d)AMP
Correct answer is option 'C'. Can you explain this answer?
Which of the following is an allosteric inhibitor of phosphofructokinase?
a)
Fructose 1,6-bisphosphate
b)
ADP
c)
ATP
d)
AMP
|
|
Orion Classes answered |
ATP acts as an allosteric inhibitor of phosphofructokinase, signaling that the cell has sufficient energy and reducing the enzyme's activity.
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