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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Practice this question and more.

Which enzyme is the rate-limiting factor in glycolysis?

Fructose bisphosphatase 2
Isocitrate dehydrogenase
Hexokinase
Phosphofructokinase (PFK)

The correct answer is: Phosphofructokinase (PFK)

In glycolysis, phosphofructokinase (PFK) is recognized as the rate-limiting enzyme. This enzyme plays a crucial role in regulating the flow of glucose through the glycolytic pathway. It catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate and is an important control point in the metabolic pathway. PFK is allosterically regulated by several molecules, which allows the cell to respond to its energy needs: ATP acts as an inhibitor, indicating high energy levels, while ADP and AMP stimulate PFK, suggesting that the cell requires more energy. This regulatory mechanism ensures that glycolysis proceeds at an appropriate rate based on the cellular conditions. The other enzymes mentioned do not serve as the primary regulatory points in glycolysis. Fructose bisphosphatase 2 is involved in gluconeogenesis, not glycolysis. Isocitrate dehydrogenase is a key enzyme in the citric acid cycle, and hexokinase catalyzes the first step of glycolysis but is not the main regulatory step. Thus, when considering the control of glycolytic flow, phosphofructokinase is essential as the rate-limiting factor.