1. Gluconeogenesis
Mainly occurs in cytosol
Some precursors are produced in mitochondria
Takes place in liver and kidney
Synthesis of glucose or glycogen from non
carbohydrates like pyruvate, lactate glucogenic
amino acids, glycerol and propionic acid
Pathway involves steps of TCA cycle and reversal of
glycolysis
The irreversible steps of glycolysis are catalysed by
Hexokinase
Phosphofructokinase and
Pyruvate kinase
These three stages bypassed by alternate enzyme
specific to gluconeogenesis
They are called as key enzymes of gluconeogenesis

2. 1. Pyruvate carboxylase
2. Phosphoenolpyruvate carboxykinase (PEPCK)
3. Fructose 1,6- Bis phosphatase
4. Glucose 6-phosphatase
The pathway meet the needs of the body for
glucose
Continuos supply of glucose required as a source
of energy for the CNS, Brain, RBC and skeletal
muscle during starvation

5. Substrates for Gluconeogenesis
Gly, Ala, Ser, Thr, Cys, Trp  pyruvate oxaloacetate
Phe, Tyr, fumarate
Asp, Asn
Arg, His,Glu, gln, proKGoxaloacetateGlucose
Val, isoleucine, Met  succinyl CoA
Propionyl CoA  succinyl CoA  oxaloacetate

7. Cori’s Cycle
Glucose/Glycogen converted to lactate in the muscle and this lactate is converted back to glucose in liver
During active muscle contraction glycogen breaks down to generate glucose

9. Regulation of gluconeogenesis
The glucagon and the availability of substrates mainly regulate gluconeogenesis
Glucagon & glucocorticoid  gluconeogenesis.
Insulin inhibit gluconeogenesis
Glucogenic amino acids have stimulating effect on key gluconeogenic enzymes
* Acetyl CoA promotes gluconeogenesis
Starvationexcessive lipolysis in adipose
tissues acetyl CoA accumulates in the liver, acetyl CoA stimulate gluconeogenic enzymes.