Glucogenesis Flashcards
What is the process of gluconeogenesis?
The production of glucose and it is similar to the reverse of glycolysis. The enzymes of the three irreversible steps of glycolysis are different to that of gluconeogenesis.
Working backwards, what is the first step that differs from glycolysis?
In glycolysis the last step is the conversion of PEP to pyruvate using pyruvate kinase. For gluconeogenesis, it can’t do the reverse in one step.
First you need to convert pyruvate to oxaloacetate.
- Bicarbonate is added to pyruvate
- Pyruvate carboxylase catalyses this
- ATP produces ADP and Pi
- Oxaloacetate is produced
- Biotin is used as a cofactor
- Oxaloacetate reacts with GTP
- PEP carboxkinase is used as an enzyme
- GTP is converted to GDP
- CO2 is released
- PEP is produced
What is the second step that differs from glycolysis?
In glycolysis the second irreversible step is conversion of fructose-6-phosphate to fructose-1,6-bisphosphate using PFK-1.
Fructose-1,6-bisphosphate in gluconeogenesis is converted into fructose-6-phosphate using fructose-1,6-bisphosphatase as the enzyme.
Phosphatase is an enzyme that catalyses the cleavage of a phosphate to yield the dephosphorylated product and Pi. H20 is also used up.
What is the third step that differs from glycolysis?
In glycolysis the first irreversible step is conversion of glucose to glucose-6-phosphate.
In gluconeogenesis, glucose-6-phosphate is converted to glucose by the enzyme glucose-6-phosphatase.
It occurs in the lumen of the ER in hepatocytes of the liver and in the cortex of the kidney.
