Lecture (4) Gluconeogenesis Flashcards
Site of gluconeogenesis…………….. and………..
cytosol and mitochondria in liver and kidneys
Fatty acids cannot produce glucose, Why?
Most fatty acids yield only acetyl-CoA.
•Acetyl-CoA cannot be provided for net synthesis of glucose as pyruvate dehydrogenase complex (PDH) reaction is irreversible. So, acetyl CoA can not be converted to pyruvate.
…………… is A metabolic pathway in which lactate is produced by anaerobic glycolysis in muscles is transported to the liver and converted to glucose, which then returns to the muscles and is cyclically metabolized back to lactate.
(Cori cycle) (Lactic acid cycle)
write a short note about the Cori cycle.
A metabolic pathway in which lactate is produced by
anaerobic glycolysis in muscles is transported to the liver and converted to glucose, which then returns to the muscles and is cyclically metabolized back to lactate.
Gluconeogenesis of glycerol occurs in the liver instead of Adipocytes. why?
Adipocytes lack glycerol kinase & cannot phosphorylate glycerol.
write a short note about the Gluconeogenesis
via glycerol.
Glycerol is released from triacylglycerols (TAG) in adipose tissue→ blood→ liver.
•Glycerol→ glycerol 3-Pby glycerol kinase (in the liver).
•Glycerol 3-P→ oxidized to dihydroxyacetone-P by glycerol 3-P dehydrogenase.
………………… are the major sources of Glucose during a
prolonged fasting.
Glucogenic amino acids derived from hydrolysis of tissue proteins
mention The irreversible reactions (Energy barriers that obstruct a simple reversal of glycolysis).
1- Between pyruvate and phosphoenolpyruvate Pyruvate kinase
2- Between fructose 1,6-bisphosphate and fructose -6p. PFK1
3- Between glucose-6-phosphate and glucose Glucokinase
how can the glucagon stimulate gluconeogenesis?
1) Induction of biosynthesis of enzymes of gluconeogenesis.
2) Covalent modification: Glucagon stimulates the conversion of Pyruvate kinase to its inactive form (phosphorylated form).
This decreases the conversion of PEP to Pyruvate, so divert PEP to glucose.
the Allosteric inhibition by AMP inhibits
a- Pyruvate carboxylase
b- F-1,6 bisphosphatase.
c- Pyruvate kinase
b- F-1,6 bisphosphatase.
Allosteric activation by acetyl CoA activates
a- Pyruvate carboxylase
b- F-1,6 bisphosphatase.
c- Pyruvate kinase
a- Pyruvate carboxylase
how to overcome pyruvate kinase?
1) Pyruvate is converted to oxaloacetate (Reaction one → carboxylation) By Pyruvate Carboxylase. then Oxaloacetate is reduced to malate, by malate dehydrogenase, which can be transported from the mitochondria to the cytosol, where it is reoxidized to OAAby cytosolic malate dehydrogenase.
Pyruvate carboxylation occurs in………
in mitochondria
Conversion of oxaloacetate to phosphoenolpyruvate (PEP) occurs by…………
By PEP carboxykinase
decarboxylation, phosphorylation
decarboxylation, phosphorylation of oxaloacetate to phosphoenolpyruvate occur in………..
cytosol
