Advanced Dental Admission Test (ADAT)

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Prepare for the Advanced Dental Admission Test. Study with flashcards and multiple choice questions, with hints and explanations provided for each question. Strengthen your readiness for success!

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What role does Phosphofructokinase (PFK) play in cellular metabolism?

It accelerates the TCA Cycle
It serves as a gluconeogenesis cofactor
It acts as a rate-limiting enzyme in glycolysis
It enhances insulin secretion

The correct answer is: It acts as a rate-limiting enzyme in glycolysis

Phosphofructokinase (PFK) is a crucial enzyme in the process of glycolysis, which is the metabolic pathway that converts glucose into pyruvate, generating energy in the form of ATP. PFK is recognized as a rate-limiting enzyme in this pathway because it catalyzes one of the key regulatory steps: the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. This step is critical because it is irreversible and effectively commits the glucose molecule to further breakdown for energy production. The regulation of PFK activity plays a significant role in controlling the overall rate of glycolysis, responding to various cellular signals regarding energy demand, such as levels of ATP or ADP. When energy is plentiful, high levels of ATP inhibit PFK, slowing down glycolysis, while when energy is low, increased levels of ADP and AMP activate PFK, facilitating the process to produce more ATP. This regulation underscores PFK's central function in the metabolic pathways that manage energy production, indicating why it is considered a rate-limiting enzyme in glycolysis specifically. Understanding PFK's role highlights the intricacies of metabolic control in cellular physiology.