Review 2-gluconeogenesis Flashcards
gluconeogenesis
synthesis of glucose from noncarbohydrate precursors (pyruvate, lactate, glycerol, glucogenic amino acid
**Requires ATP
where does gluconeogenesis take place?
mostly liver some extent kidney
How is Pyruvate converted to phosphoenolpyruvate (PEP)?
Pyruvate>Oxaloactate
Pyruvate Carboxylase
Oxaloacetate>phosphoenolpyruvate
PEP carboxykinase
Requires Bicarb and biotin cofactor (expends ATP)
What are the gluconeogenic Precursors for pyruvate?
lactate and amino acids (ie alanine)
What are the gluconeogenic Precursors for oxaloacetate?
Amino acids (ie aspartate)* Propionate
What are the gluconeogenic Precursors for triose phosphates?
glycerol*
fructose
Cori Cycle
Glucose-lactate cycle
RBC and skeletal muscle
Alanine Cycle
Alanine
Muscle cell
(additional ATP for ureagenesis)
What serves as the major source for ATP necessary for Gluconeogeneisis?
oxidation of fatty acids
Four enzymes required to reverse 3 irreversible steps of glycolysis
- pyruvate carboxylase (mito)
- Phosphoenolpyruvate (PEP) carboxykinase
- Fructose 1,6 bisphosphatase
- glucose 6 phosphate
Pyruvate Carboxylase Deficiency Symptoms
Failure to thrive, developmental delay, recurrent seizures, and metabolic acidosis
What happens when there is a lack of pyruvate carboxylase?
Accumulation of Pyruvate in plasma
- elevated lactic acid
- elevated alanine
Von Gierke disease
glucose 6-phosphatase deficiency
Symptoms of glucose-6-phosphatase deficiency (Von Gierke Disease)
Poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in liver, elevated serum uric and elevated serum lactate
-Disrupts gluconeogenesis and glycogenolysis (both get to glucose 6 phosphate and cant go any further to glucose)
CANT GET GLUCOSE
ethanol metabolism
Hypoglycemia
High NADH/NAD ratio
Opposes Gluconeogenesis because you don’t have precursors
Increased NAHD–>
Pyruvate and oxaloacetate> lactate and malate
No precursors
Increased NADH–>increased Lactate
