MCAT glycolysis regulation
High-yield facts and key regulatory mechanisms of glycolysis for MCAT preparation, focusing on enzymes, allosteric regulation, and feedback inhibition.
Quiz(36 questions)
1. What effect does insulin have on the enzyme phosphofructokinase in glycolysis?
Terms in this Study Set(36)
Enzymes of Glycolysis(16)
Hexokinase function in glycolysis?
Converts glucose to glucose-6-phosphate (G6P). Uses ATP, irreversible step.
PFK-1 regulation by ATP.
High ATP inhibits PFK-1, slowing glycolysis.
What does pyruvate kinase do?
Converts phosphoenolpyruvate (PEP) to pyruvate, producing ATP.
Fructose-2,6-bisphosphate role?
Activates PFK-1 and promotes glycolysis.
True or False: Glucagon stimulates glycolysis.
False: Glucagon inhibits glycolysis, promoting gluconeogenesis.
Hexokinase vs. Glucokinase: major difference?
Hexokinase: low Km, found in most tissues. Glucokinase: high Km, liver-specific.
What stimulates Pyruvate Kinase?
Fructose-1,6-bisphosphate activates pyruvate kinase.
Key substrate for PFK-1?
Fructose-6-phosphate is the substrate, ATP is the inhibitor.
Insulin effect on glycolysis?
Stimulates glycolysis by promoting PFK-1 and Pyruvate Kinase.
Step in glycolysis where ATP is produced?
ATP produced at phosphoglycerate kinase and pyruvate kinase steps.
What inhibits hexokinase?
Glucose-6-phosphate inhibits hexokinase through feedback inhibition.
Fructose-1,6-bisphosphate production step?
Produced from fructose-6-phosphate by PFK-1.
Key cofactor for glyceraldehyde-3-phosphate dehydrogenase?
NAD+ is the essential cofactor for this enzyme.
What does high AMP indicate?
High AMP activates PFK-1, signaling low energy.
Pyruvate Kinase: Allosteric inhibitors?
ATP and acetyl-CoA inhibit pyruvate kinase activity.
Conversion of phosphoenolpyruvate to pyruvate: what is produced?
Produces ATP through substrate-level phosphorylation.
Allosteric Regulators(12)
Which molecules inhibit phosphofructokinase-1 (PFK-1)?
Citrate and ATP are inhibitors. They signal high energy levels, reducing glycolysis.
What activates phosphofructokinase-1 (PFK-1)?
Fructose-2,6-bisphosphate and AMP activate PFK-1, promoting glycolysis.
True or False: ATP is a positive allosteric regulator of PFK-1.
False. ATP inhibits PFK-1, signaling sufficient energy.
Fill in the blank: Fructose-2,6-bisphosphate is a potent ________ of PFK-1.
activator
Cause → Effect: High levels of citrate in the cell.
Cause glycolysis inhibition via PFK-1.
Which enzyme is activated by AMP?
Phosphofructokinase-1 (PFK-1) is activated by AMP, indicating low energy.
Compare: ATP vs. AMP on PFK-1 activity.
ATP inhibits; AMP activates. They indicate cellular energy status.
What does elevated fructose-2,6-bisphosphate indicate?
It indicates a need for increased glycolysis for energy production.
True or False: Citrate is a substrate for the glycolytic pathway.
False. Citrate is a TCA cycle intermediate, not a glycolytic substrate.
Which allosteric regulator promotes pyruvate kinase activity?
Fructose-1,6-bisphosphate activates pyruvate kinase, enhancing glycolysis.
What is the effect of high ATP on pyruvate kinase?
High ATP inhibits pyruvate kinase, slowing glycolysis and energy production.
Name an allosteric inhibitor of pyruvate kinase.
Alanine is an inhibitor, signaling sufficient amino acid availability.
Hormonal Regulation(8)
Insulin effect on glycolysis?
Insulin promotes glycolysis by activating key enzymes like pyruvate kinase and phosphofructokinase, enhancing glucose conversion to energy.
True or False: Glucagon stimulates glycolysis.
False. Glucagon inhibits glycolysis and promotes gluconeogenesis, increasing blood glucose levels.
Role of epinephrine in glycolysis?
Epinephrine enhances glycolysis during stress by activating glycogen breakdown and promoting glucose availability.
Fill in the blank: Cortisol __________ glycolysis.
inhibits
Comparison: Insulin vs Glucagon on glycolysis
Insulin: Stimulates glycolysis; Glucagon: Inhibits glycolysis.
Effect of high blood glucose on glycolysis?
Increased insulin secretion leads to enhanced glycolysis, promoting energy production.
Cause → Effect: Increased AMP levels?
Increased AMP activates phosphofructokinase, stimulating glycolysis.
Hormone responsible for glycolysis activation?
Insulin - it facilitates glucose uptake and metabolism.
Questions in this Study Set(36)
1. What effect does insulin have on the enzyme phosphofructokinase in glycolysis?
2. What is the primary function of hexokinase in glycolysis?
3. Which molecule acts as a potent inhibitor of phosphofructokinase-1 (PFK-1)?
4. Which hormone is primarily responsible for the inhibition of glycolysis during fasting?
5. Which molecule acts as a potent inhibitor of PFK-1?
6. What effect does elevated AMP have on PFK-1 activity?
7. How does epinephrine affect glycolysis during times of stress?
8. What is the role of pyruvate kinase in glycolysis?
9. Which of the following is NOT an allosteric regulator of pyruvate kinase?
10. Fill in the blank: Glucagon __________ glycolysis.
11. How does fructose-2,6-bisphosphate affect PFK-1 activity?
12. Fill in the blank: High levels of ATP indicate a need for ________ glycolysis.
13. Which of the following is NOT a function of insulin in glycolysis?
14. True or False: Glucagon stimulates glycolysis in the liver.
15. True or False: Fructose-2,6-bisphosphate is an inhibitor of PFK-1.
16. What is the effect of increased AMP levels on glycolysis?
17. What distinguishes hexokinase from glucokinase?
18. Cause → Effect: High citrate levels in the cell result in ________ glycolysis.
19. In the context of glycolysis, which hormone's primary role is to increase blood glucose levels?
20. What activates pyruvate kinase?
21. Which enzyme is inhibited by alanine?
22. Which hormone would you expect to be elevated after a carbohydrate-rich meal, impacting glycolysis?
23. What is the key substrate for PFK-1?
24. How does ATP function as an allosteric regulator of PFK-1?
25. How does insulin affect glycolysis?
26. Which molecule is a positive allosteric regulator of pyruvate kinase?
27. At which steps in glycolysis is ATP produced?
28. True or False: AMP is an allosteric inhibitor of phosphofructokinase-1 (PFK-1).
29. What inhibits hexokinase activity?
30. Which of the following allosteric regulators signals high energy status?
31. What is produced from fructose-6-phosphate by PFK-1?
32. Compare: What is the main effect of AMP versus ATP on glycolysis?
33. What cofactor is essential for glyceraldehyde-3-phosphate dehydrogenase?
34. What indicates a high AMP level in a cell?
35. Which of the following serves as allosteric inhibitors of pyruvate kinase?
36. What is produced during the conversion of phosphoenolpyruvate to pyruvate?
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