Alternative glycolytic pathways — Flashcards

Flashcard 1: Fructose-1,6-bisphosphate is converted into _____ and dihydroxyacetone-phosphate via the enzyme aldolase 'A'

Answer: glyceraldehyde-3-phosphate

Flashcard 2: Thiamine pyrophosphate (B1) is a cofactor for the enzyme _____ (glycolysis)

Answer: pyruvate dehydrogenase

Flashcard 3: What substrate overrides inhibition of the enzyme phosphofructokinase-1 by ATP in the liver? _____

Answer: Fructose-2,6-bisphosphate

Flashcard 4: Pyruvate kinase is regulated via feed-forward activation by _____

Answer: fructose-1,6-bisphosphate

Flashcard 5: In erythrocytes, 90% of glucose is used for _____

Answer: glycolysis

Flashcard 6: What is the function of the bifunctional enzyme Phosphofructokinase-2/Fructose bisphosphatase-2 (PFK-2/FBP-2)?

Answer: A bifunctional enzyme that regulates the levels of Fructose-2,6-bisphosphate (F-2,6-BP), thereby balancing glycolysis and gluconeogenesis.

Extra: In the well-fed state, PFK-2 is active (increased F-2,6-BP) → stimulates Glycolysis.\nIn the fasting state, FBP-2 is active (decreased F-2,6-BP) → stimulates Gluconeogenesis.

Flashcard 7: Where does glycolysis take place?

Answer: cytoplasm

Flashcard 8: What is the rate-limiting enzyme of glycolysis?

Answer: Phosphofructokinase-1 (PFK-1)

Extra: The three irreversible steps of glycolysis are catalyzed by:\n1. Hexokinase/Glucokinase\n2. Phosphofructokinase-1 (Rate-limiting step)\n3. Pyruvate kinase\n\nPFK-1 is inhibited by ATP and Citrate, and activated by AMP and Fructose-2,6-bisphosphate.

Flashcard 9: What enzyme converts pyruvate to lactate?

Answer: lactate dehydrogenase (LDH)

Flashcard 10: Role and primary locations of Glucokinase

Answer: Catalyzes the first step of glycolysis and glycogen synthesis (Glucose → G6P) in the liver and pancreatic β-cells.

Extra: Traps glucose within the cell by phosphorylation. Induced by insulin. Compared to Hexokinase: High Km (lower affinity) and High Vmax (higher capacity).