An enzyme used in gluconeogenesis but NOT glycolysis is:Group of answer choicesglucose 6-phosphatasephosphofructokinase-1pyruvate kinasehexokinase

1. Break Down the Problem

We need to identify which enzyme is involved specifically in gluconeogenesis and not in glycolysis from the provided options.

2. Relevant Concepts

• Gluconeogenesis is the metabolic pathway that generates glucose from non-carbohydrate substrates.
• Glycolysis is the process of breaking down glucose to produce energy.
• Key enzymes to consider:
  • Glucose 6-phosphatase (important in gluconeogenesis, removes a phosphate group from glucose 6-phosphate).
  • Phosphofructokinase-1 (PFK-1 is a key regulatory enzyme in glycolysis).
  • Pyruvate kinase (catalyzes the final step of glycolysis).
  • Hexokinase (phosphorylates glucose to glucose 6-phosphate in glycolysis).

3. Analysis and Detail

1. Glucose 6-phosphatase: This enzyme is crucial for gluconeogenesis, facilitating the final step that converts glucose 6-phosphate to glucose, releasing free glucose into the bloodstream. It does not play a role in glycolysis.
2. Phosphofructokinase-1 (PFK-1): A regulatory enzyme in glycolysis, it catalyzes the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate. It does not participate in gluconeogenesis.
3. Pyruvate kinase: This enzyme acts in glycolysis to convert phosphoenolpyruvate to pyruvate, thus it does not function in gluconeogenesis.
4. Hexokinase: This enzyme phosphorylates glucose to glucose 6-phosphate, which is a key step in glycolysis but not in gluconeogenesis.

4. Verify and Summarize

Upon reviewing the roles of each enzyme, it is confirmed that glucose 6-phosphatase is the only enzyme among the listed options that participates in gluconeogenesis and not in glycolysis.

Final Answer

The enzyme used in gluconeogenesis but NOT in glycolysis is glucose 6-phosphatase.