Gluconeogenesis Flashcards
What is gluconeogenesis?
The formation of glucose from non-carbohydrate sources
What organs does gluconeogenesis mainly occur in? Why?
The liver and kidneys because they are the only organs that can export glucose via the GLUT2 pumps
Where in the cell does gluconeogenesis occur?
Both in the cytoplasm and mitochondria
List 4 substrates for gluconeogenesis
- Lactate
- Glycerol
- Glucogenic Amino Acids
- Propionate
What are the main exporters of lactate?
Muscle cells and RBCs
What are the two main glucogenic amino acids?
alanine and glutamine
What is an important fact about the role of propionate in some species?
It is the principal substrate for ruminants. It is produced by rumen microbes.
Why isn’t gluconeogenesis just glycolysis in reverse?
There are 3 irreversible steps in glycolysis that you need to bypass with other rxns
What is the first “bypass” step utilized by glyconeogenesis?
Pyruvate - PEP
-Pyruvate - OAA via Pyruvate carboxylase
-OAA-PEP via PEP carboxykinase
What is the rate limiting step of gluconeogeneis?
Pyruvate- PEP
Specifically OAA-PEP via PEP carboxykinase
What is the second “bypass” step utilized by glyconeogenesis?
Fructose 1,6 bisphosphate - F-6-P via F 1,6 bisphosphatase
What is the third “bypass” step utilized by glyconeogenesis?
G-6-P to Glucose via G-6-phosphatase
Which of the “bypass” enzymes is liver/kidney specific?
G-6 phosphatase
What key molecule can regulate BOTH glycolysis and gluconeogenesis at the same time?
Fructose 2,6 bisphosphate
-High = glycolysis
-Low = gluconeogenesis
What is role to muscles play in gluconeogenesis?
-Exports alanine, where it is transaminated to pyruvate in the liver
- Lactate is exported to the liver where it can enter as pyruvate
