Gluconeogenesis Flashcards
What is gluconeogenesis?
Involves making glucose from non-carbohydrate molecules
Where does gluconeogenesis mainly occur?
- Liver
- Kidneys
What 3 steps which are different in gluconeogenesis compared to glycolysis?
- Pyruvate to phosphoenolpyruvate
- Fructose-1,6-bisphosphate to fructose-6-phosphate
- Glucose-6-phosphate to glucose
Where does the conversion of pyruvate to phosphoenolpyruvate occur?
The mitochondrial matrix
How is oxaloacetate transported out of the mitochondrial matrix to the cytosol?
Via malate shuttle
Why can’t oxaloacetate be moved out of the mitocondrial matrix?
There is no oxaloacetate transporter
How does the malate shuttle work?
- Oxaloacetate is converted to malate, whilst NADH + H+ produces NAD+
- The malate then moves through the transporter
- The reverse reaction occurs in the cytosol
What type of enzyme is fructose-1,6-bisphosphate?
Allosteric
How does glucose-6-phosphatase work?
- It is a membrane bound protein, with the active site in the ER lumen
- Glucose-6-phosphate is first transported into the ER
- the glucose and Pi are transported back out
How many ATPs are used in gluconeogenesis?
4
How many GTPs are used in gluconeogenesis?
2
What occurs in the cori cycle?
Lactate made by anaerobic glycolysis in muscle is recycled back to glucose in the liver
What inhibits pyruvate carboxylase?
ADP
What stimulates pyruvate carboxylase?
Acetyl CoA
What inhibits phospoenol pyruvate carboxykinase?
ADP
