Endocrine - Gluconeogenesis Flashcards
What two parts/organs of the body require glucose for fuel?
Brain and erythrocytes
Is gluconeogenesis a simple reversal of glycolysis?
No
Where does gluconeogenesis take place?
Liver 90%
Kidney 10%
What 4 enzymes are needed in gluconeogenesis to overcome the irreversible steps of glycolysis?
Pyruvate carboxylase
PEP carboxykinase
Fructose-1,6-bisphosphatase
Glucose-6-phosphatase
What converts pyruvate to oxaloacetate? What does it require?
Pyruvate Carboxylase
ATP
What converts Oxaloacetate to PEP? What does it require?
PEP carboxykinase
GTP
Is PEP in glycolysis?
Yes, 2nd to last step
What converts Fructose-1,6-bisphosphate to Fructose-6-phosphate?
Fructose-1,6-bisphosphatase
What converts Glucose-6-phosphate to glucose?
Glucose-6-phosphatase
Where does the conversion of pyruvate to Oxaloacetate occur? What does it require as a prosthetic group? Why
Mitochondria
Biotin
Needed to add CO2 (new carbon atom)
What is pyruvate carboxylase reaction tightly regulated by?
Acetyl-CoA
What is the purpose of the malate shuttle and aspartate shuttle?
To get oxaloacetate from inside mitochondria to cytosol
When does the newly added CO2 get removed from oxaloacetate? Why was it added in the first place?
Gets removed by phosphoenolpyruvate carboxykinase
Needed temporarily so phosphate could be added
What is the major control point of gluconeogenesis?
Fructose-1,6-bisphosphatase -> Fructose-6 phosphate
Irreversible reaction!
Where is the enzyme that converts Glucose-6-phosphate to glucose located?
Endoplasmic reticulum
What is the energy cost of 1 glucose molecule being made through gluconeogensis?
4ATP
2GTP
2NADH
=12ATP
What two ways of regulating gluconeogenesis exist?
Allosteric (local)
Hormonal
What stimulates PKF1 and inhibits Fructose-1,6-bisphosphatase?
AMP
What inhibits PFK-1?
ATP, citrate
What inhibits pyruvate kinase?
ATP and alanine
What stimualtes PK?
Fructose-1,6-BP
What two hormones regulate gluconeogensis in the lvier? How?
Insulin - inhibits gluconeogensis (stimulates glycolysis)
Glucagon - stimulates gluconeogensis (inhibits glycolysis)
What is the intermediate in the control step of gluconeogenesis?
Fructose-2,6-bisphophate
Is pyruvate kinase more active or less active phosphorylated?
LEss active
What hormone helps dephosphorylate PK?
Insulin
What hormone helps phosphorylate PK?
Glucagon
What is the Cori cycle?
Cycle of lactate to liver and glucose to erythrocytes and muscle
How does glycerol enter gluconeogenesis?
As DHAP (dihydroxyacetone phosphate)
What cycle can propionyl-CoA enter? How?
TCA cycle
Converted to succinyl-CoA
