MB - Gluconeogenesis Flashcards
What is gluconeogenesis?
The synthesis of new glucose molecules from other molecules
Why does gluconeogenesis need to occur?
Glycogen stores in the liver are limited
Why can FA not be converted to glucose?
Our body does not contain the enzymes for it
Why can glycolysis not be reversed to produce glucose?
There are three irreversible steps in glycolysis
Describe the alternative reverse pathway to the irreversible PEP –> Pyruvate step
-
Step 1- Pyruvate Carboxylase
(Mitochondria)
Pyruvate –> Oxaloacetate -
Step 2- PEP Carboxykinase
(Cytoplasm)
Oxaloacetate –> PIP
Describe the alternative reverse pathway to the irreversible F-6-P –> F-1,6-bisP step
F-1,6-bisP + H2O –> F-6-P + Pi
* F-1,6-bisphosphatase
Hydrolysis
Describe the alternative reverse pathway to the irreversible Glucose –> G-6-P step
G-6-P + H2O –> Glucose + Pi
* Glucose-6-phosphatase
Hydrolysis
What are the 2 stores of pyruvate that allow for gluconeogenesis levels to be mantained?
1) Lactate - Cori cycle
2) Glucogenic amino acids
What is the Cori cycle?
- Lactate is anaerobically produced in the muscles
- The lactate is transported to the liver
- (Liver) Lactate -> Pyruvate –> Glucose
- Glucose is cyclically trasnported to muscles
- (Muscles) Glucose –> Pyruvate –> Lactate
Levels of Pyruvate are mantained
What are glucogenic amino acids?
An amino acid that can be converted into glucose through gluconeogenesis
What amino acid is released into the blood by muscle catabolism?
Alanine
(Converted into pyruvate)
What can glycerol be converted into?
Glycerol –> DHAP or G-3-P
* Both can enter the pathway and continue with gluoneogenesis
What 3 other molecules can enter the gluconeogenesis pathway?
1) Fructose
2) Galactose
3) Mannose
