Gluconeogenesis Flashcards
What is the most central molecule in gluconeogenesis?
Glucose 6 phosphate at is goes to all the other carbohydrate components.
What is the general process of gluconeogenesis?
3 carbon molecules to 6 carbon.
What needs to be bypassed in gluconeogenesis? How is this bypassed?
Hexokinase - taking phosphate off F-1,6 bisphosphate by make F-1,6- bisphosphatase making fructose 6 phosphate
PFK-1 - taking phosphate off glucose 6-phosphate to release glucose into the blood via glucose 6 phosphatase
What are the steps to bypassing the glycolytic energy release steps? What enzymes are used for this?
Turn pyruvate into oxaloacetate (pyruvate carboxylase)
Turn oxaloacetate into phosphoenolpyruvate (PEP carboxykinase)
The enzymes for the glycolytic energy release step ( pyruvate to phosphoenolpyruvate - 1st step) are also found outside the liver. Why is this helpful?
Enables glycerol to be made from pyruvate - even if cant undergo whole gluconeogenesis.
Draw the G6Pase system.
Card 15
Isomerisation between glucose and fructose forms happens at top of glycolysis. What is needed? What does this mean?
OH group at 2 prime position. Cant do a reaction without it. G6P trapped inside cell forever.
What is the benefit of highlighting a molecule at the 2’ position of 2-Fluro-2-deoxyglucose (FdG) as something detectible?
It cant be metabolised any further without a OH group at the 2’ position and so it can be used to detect areas using a lot of glucose - cant leave the cell.
How can FdG highlighting be used in cancer diagnosis?
Shows up in areas of high glucose utilisation - cancer cells use a lot of glucose. FdGP inhibits glycolysis and cancer cells rely heavily on the formation of G6P.
What is the role of Fructose 2-6-bisphosphate? How does it do this?
Key regulator of PFK-1 (for glycolysis) and FBPase-1 (for gluconeogenesis). Changes allosterically the affinity of the enzymes for their substrates.
What does F26BP do for PFK 1 and FBPase activity?
Increases activity of PFK1 and decreases activity of FBPase-1.
PFK-2 and FBPase-2 are connected how? What is this catalysed by?
They are the same enzyme swapping from one form to the other by reversible phosphorylation. Interconversion catalysed by protein kinase A which is sensitive to glucagon/insulin.
During starvation _____ increase leads to increase in concentration of _______ which decreases concentration of ______. What does this lead to?
Glucagon. cAMP. F26BP. There is no stimulus for PFK so no glycolysis and no inhibition of F16BP.
