What statements are TRUE? Phosphofructokinase (PFK) is:i) activated by elevated ATP/ADP ratiosii) activated by AMPiii) inhibited by AMPiv) requires fructose 6 phosphatev) a rate limiting enzyme of glycolysisvi) reversiblevii) the commitment step in glycolysisviii) requires ATP
Question
What statements are TRUE? Phosphofructokinase (PFK) is:i) activated by elevated ATP/ADP ratiosii) activated by AMPiii) inhibited by AMPiv) requires fructose 6 phosphatev) a rate limiting enzyme of glycolysisvi) reversiblevii) the commitment step in glycolysisviii) requires ATP
Solution
i) False - Phosphofructokinase (PFK) is inhibited, not activated, by elevated ATP/ADP ratios. This is because high ATP/ADP ratios indicate that there is plenty of energy available, so the cell does not need to break down more glucose for energy.
ii) True - PFK is activated by AMP. AMP is a signal that the cell is running low on energy, so it stimulates PFK to start breaking down more glucose.
iii) False - As mentioned above, PFK is activated, not inhibited, by AMP.
iv) True - PFK does require fructose 6-phosphate. It catalyzes the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate, which is a key step in glycolysis.
v) True - PFK is a rate-limiting enzyme of glycolysis. This means that it is one of the slowest steps in the pathway, and therefore determines the overall rate of glycolysis.
vi) False - The reaction catalyzed by PFK is not reversible. This is one of the reasons why it is a rate-limiting step.
vii) True - The reaction catalyzed by PFK is often considered the "commitment step" in glycolysis, because once fructose 6-phosphate has been converted to fructose 1,6-bisphosphate, it is committed to being fully broken down in the rest of the glycolysis pathway.
viii) True - PFK does require ATP. It uses one molecule of ATP to add a phosphate group to fructose 6-phosphate.
Similar Questions
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