Unit 4: Chapter 17, Regulation of Gluconeogenesis and Glycolysis Flashcards
(26 cards)
gluconeogensis and glycolysis are _________ _________
reciprocally regulated
Ex. Glycolysis will predominate when gluconeogenesis is inhibited and vise versa
Reciprocally regulated
when one is activated, other is inhibited
___ will predominate when glucose is abudant and ATP is needed
glycolysis
___ will predominate when glucose is scarce
gluconeogenesis
If both gluconeogenesis and glycolysis are active at the same time..
the net result would be the hydrolysis of 4 nucleotide triphosphates per reaction cycle since it is futile cycle
What is key regulation enzyme in gluconeogenesis?
Intervoncversion of fructose 6 phosphate and fructose 1,6 biphosphate catalyzed by fructose 1,6 biphosphatase
How is fructose 1,6 biphosphatase inhibited?
Inhibited by ADP, low energy charge
Since process is highly expensive when energy charge is low, the key enzyme is inhibited
How is fructose 1,6 biphosphatase activated?
Activated by high energy change
Evaluate following situation: When energy is needed and AMP concentration is high
- if AMP is high indicates low energy
- Glycolysis will be activated and gluconeogenesis will be inhibited
- AMP activates PFK and inhibits F1,6 biphosphatase
Evaluate following situation: When energy level is high, ATP level is high, and citrate concentration is high
- citrate indicates energy charge is high and biosynthetic intermediates
- glycolysis inhibited and gluconeogenesis will be activated
- PFK will be inhibited and F 1,6 biphosphatase will be activated
What indicates cell is rich in biosynthetic precursors and anabolic pathways are favored (require energy so gluconeogenesis)?
Citrate, alanine, CoA, and ATP
Glycolysis occurs where
Cytosol
Gluconeogenesis occurs where
Liver and kidneys
Balance between glycolysis and gluconeogenesis in liver is sensitive to
maintain blood glucose concentration
After a meal, blood glucose is abundant which effects
- Hormone glucagon concentration in blood falls and insulin concentration rises
- Gluconeogenesis will be inhiited and glyucolysis will predomiante
What is a potent activator of PFK?
Fructose 2,6 biphosphate
Fructose 2,6 biphopshate inhibits what in gluconeogenesis
Fructose 1,6 biphosphate
How is the amount of fructose 2,6 biphosphate controlled of rise and fall in blood glucose concentration?
Controlled by bifunctional regulaotry enzyme PFK2 and fructose phosphatase 2
Both PFK2 and FBPase 2 are present in ________
single polypeptide chain
How are PFK2 and FBPase controlled by
phosphorylation of single serine residue by protein kinase / phosphoprotein phosphatase
PFK2/FBPase 2: When glucose level is low, glucagon hormone level is up
- Protein kinase A will be activated and will phosphorylate serine on PFK2
- PFK2 inactivated and FBPase 2 activated
- FPase 2 catalyzed fructose 2,6 biphosphaate to fructose 6 phosphate (dephosphorylation)
- concentration is lower
- glycolysis in ihhibited and glucogenesis is activated
PFK2/ FBPase 2: When glucose level is high, insulin concentration rises
- Stimulates glycolysis and gluconeogensis inhibited
- Remove phosphase in PFK2 by phosphoprotein phosphatase
- PFK2 activated and FBPase 2 inhibited
- PFK2 catalyzed fructose 6 phosphate to fructose 2,6 biphosphate (phosphorylation)
Coordinated control of glycolysis and glucogenesis is faciliated by
location of kinase and phosphotase domain on same polypeptide chain as regulatory domain
What does cori cycle refer to?
- Recyclign of glucose due to glycolysis in muscle and gluconeogensis in liver
- Glycolysis in fast twitch skeletal muslce produces lactate in conditions of O2 debt
- Glucogeonesis recycles lactate to glucose after it is first oxidfized to pyruvate which occurs in the liver
