Gluconeogenesis Flashcards
How does gluconeogenesis accomplish the reverse of glycolysis?
Gluconeogenesis accomplishes the reverse of glycolysis - synthesis of glucose from pyruvate using four different enzymes to replace three energetically unfavorable reactions in glycolysis for a total of 11 reaction.
What parts of the body does gluconeogenesis occur in?
Gluconeogenesis does not occur in all tissues of the body. The primary gluconeogenic organs of the body are the liver and part of the kidney.
What enzymes are unique to gluconeogenesis?
The enzymes unique to gluconeogenesis are:
Pyruvate Carboxylase and PEP carboxykinase (PEPCK) instead of Pyruvate Kinase of glycolysis
Fructose 1,6 Bisphosphatase (F1,6BPase) instead of Phosphofructokinase (PFK) from glycolysis,
Glucose-6-phosphatase (G6Pase) instead of Hexokinase from glycolysis.
How are F1,6BPase and G6Pase similar in their mechanisms? What do they avoid in doing so?
F1,6BPase and G6Pase act by similar mechanisms, clipping a phosphate from their substrates and thus avoiding synthesis of ATP, which is what would be required if the glycolysis reactions were simply reversed.
What reaction occurs in the mitochondrion?
One reaction of gluconeogenesis occurs in the mitochondrion. It is catalyzed by pyruvate carboxylase and yields the four carbon intermediate, oxaloacetate.
What reaction takes place in the lumen of the ER?
The G6Pase reaction occurs in the lumen of the endoplasmic reticulum.
How is the carboxyl group added in forming oxaloacetate?
The carboxyl group is added in forming oxaloacetate thanks to the coenzyme biotin, which carries carbon dioxide for attachment.
Where do most of the reactions take place in gluconeogenesis?
Most occur in the cytoplasm.
What does Pyruvate carboxylase require to work?
Pyruvate carboxylase uses ATP and makes oxaloacetate.
What does PEPCK require to work?
PEPCK uses GTP and breaks down oxaloacetate to PEP.
