MCAT Biochemistry Question 132: Answer and Explanation
Home > MCAT Test > MCAT biochemistry practice tests
Test Information
- Use your browser's back button to return to your test results.
- Do more MCAT biochemistry practice tests.
Question: 132
12. The unique enzymes of gluconeogenesis are used to circumvent specific irreversible steps of glycolysis. Which of the following correctly pairs an enzyme from glycolysis with its corresponding enzyme(s) used in gluconeogenesis?
- A. Phosphofructokinase-1 / fructose-1,6-bisphosphatase
- B. Pyruvate dehydrogenase / pyruvate carboxylase and phosphoenolpyruvate carboxykinase
- C. Hexokinase / glucokinase
- D. Pyruvate kinase / glucose-6-phosphatase
Correct Answer: A
Explanation:
The irreversible enzymes in glycolysis are hexokinase (or glucokinase in liver and pancreatic β-cells), phosphofructokinase-1, and pyruvate kinase. Pyruvate dehydrogenase is not considered a glycolytic enzyme because it requires the mitochondria to function. The list below shows the correct pairing of glycolytic enzymes with gluconeogenic enzymes:
- Hexokinase or glucokinase/glucose-6-phosphatase
- Phosphofructokinase-1/fructose-1,6-bisphosphatase
- Pyruvate kinase/pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK)