Gluconeogenesis Flashcards
What is gluconeogenesis?
Synthesis of glucose from non-carbohydrate sources due to lack of diet
Sites of gluconeogenesis
Cytoplasm and mitochondria; in liver (90%) and in kidneys (10%)
Alternative substrates
Major: Pyruvate Lactate Glycerol Glucogenic AA’s (except Leu)
Minor:
Propionyl CoA
When does gluconeogenesis occur?
> Fasting/starvation
Gluconeogenesis is the primary source of energy of __ and __ during starvation
CNS and Erythrocytes
During fasting/starvation, pyruvate is an intermediate in gluconeogenesis. How?
Via Glucose-alanine cycle,
Pyruvate + Glut -> ALA + alpha-Keto
A;a then carried in the blood -> liver and is reconverted to pyruvate for gluconeogenesis
Lactate as a major substrate in what cycle? Net ATP?
Cori’s cycle + Glycolysis
= -6 + 2 = -4
Glycerol as a major substrate?
Glycerol backbone used! FA can’t be used
Major amino substrate of gluconeo?
1st: ala
2nd: glutamine
Minor substrate of gluconeogenesis
- Origin
- pathway
Enters gluconeogenic process via TCA in the form of SUCCINYL COA
3 major pathways in Glycolysis that should be bypassed in Gluconeogenesis?
- PK (Pep -> Pyruvate)
- PFK1 (Fructose-6-P -> Fructose-1,6-bisP)
- Glucokinase/Hexokinase (Glucose -> Glucose-6-P)
Von Gierke’s Disease
Deficiency in Glucose-6-Phosphatase
-fasting hypoglycemia
How do these molecules enter gluconeogenesis?
- Galactose
- Fructose
-
Regulators of gluconeogenesis?
Allosteric and covalent
Role of alcohol oxidation in gluconeogenesis?
Production of NADH
=Increased NADH = inhibits Pyruvate carboxylase and PEPCK (and gluconeogenesis)
