Gluconeogenesis

Gluconeogenesis

Table of Contents

Location of Gluconeogenesis

Steps in Gluconeogenesis

Reactions involved in Gluconeogenesis

Significance of Gluconeogenesis Pathway

Associated Disease

Gluconeogenesis is the production of glucose from non-sugar precursors.

Gluconeogenesis, mainly occurs in the liver, and involves the synthesis of glucose from compounds that are not carbohydrates.

When a cell is growing on a hexose such as glucose, and obtaining glucose for polysaccharide synthesis, there is no problem.

But when the cell is growing on other carbon compounds, glucose must be synthesized. This process is called as gluconeogenesis.

Gluconeogenesis uses phosphoenolpyruvate, which is one of the intermediates of glycolysis, as starting material and travels backwards through the glycolytic pathway to form glucose.

However, it involves several enzymatic steps that do not occur in glycolysis; thus, glucose is not generated by a simple reversal of glycolysis alone.

The major precursors for gluconeogenesis are lactate, amino acids (which form pyruvate or TCA cycle intermediates), and glycerol (which forms DHAP).

The synthesis of 1 mole of glucose from 2 moles of lactate requires energy equivalent to about 6 moles of ATP.

Reactions involved in Gluconeogenesis

1.   
Conversion
of pyruvate to phosphoenolpyruvate

2.   
Conversion
of fructose 1,6-bisphosphate to fructose-6-phosphate

3.   
Conversion
of glucose-6-phosphate to glucose

Thus, the net requirements to
make one glucose molecule are:

·        
Two pyruvate.

·        
Four ATP and two GTP.

·        
Two NADH.

·        
Six H2O

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