Gluconeogenesis Flashcards
Gluconeogenesis occurs when…
hepatic glycogen is depleted
Gluconeogenesis forms glucose from:
- Lactic acid from muscle and RBC (Cori cycle)
- Amino acids from muscle protein
- Glycerol released from triglycerides in adipose tissue
Name the pathway that converts glucose to pyruvate to lactate which leaves the tissue
Glycolysis
The liver converts lactate to pyruvate to glucose which enters the blood. Which pathway is this?
Cori cycle
What is the enzyme that converts pyruvate to lactate in the liver?
Lactate dehydrogenase (LDH)
What pathway will turn muscle glucose into pyruvate then alanine entering the blood?
Gluconeogenesis (glucose-alanine cycle)
What pathway involves the liver converting alanine to pyruvate then to glucose?
Gluconeogenesis (glucose-alanine cycle)
What is the enzyme that converts alanine to pyruvate in the liver?
ALT/SGPT
For gluconeogenesis, how many ATP per pyruvate are required to generate one glucose?
Require 4 ATP per pyruvate
Which pathway provides the ATP needed for gluconeogenesis?
Beta oxidation of fats
Where in the cell does gluconeogenesis begin?
Mitochondria
Where in the cell does gluconeogenesis end?
The lumen of the endoplasmic reticulum
What is the allosteric enzyme of gluconeogenesis? Where is it?
Fructose 1,6-biphosphatase in liver and kidneys
What hormone(s) activates Fructose 1,6-biphosphatase?
Glucagon + epinephrine
Which two enzymes in gluconeogenesis require ATP?
Pyruvate carboxylase
Phosphoglycerate kinase
Which enzyme requires GTP?
PEPCK (phosphoenolpyruvate carboxykinase)
List the four enzymes unique to gluconeogenesis
- Pyruvate carboxylase
- PEPCK
- Fructose biphosphatase
- Glucose 6 phosphatase (liver only)
Which enzyme converts glycerol 3P to DHAP?
Isomerase
Which enzyme converts glycerol to glycerol 3P?
Glycerol kinase
Which enzyme will allow aspartate/asparagine into the Kreb’s cycle?
AST/SGOT
Which enzyme will allow glutamate/glutamine into the Kreb’s cycle?
Glutamate dehydrogenase
What is the mechanism for decreasing pyruvate dehydrogenase and increasing pyruvate carboxylase during gluconeogenesis?
Acetyl-CoA buildup via exercise or fasting
What is the name of the genetic disease where the enzyme glucose 6 phosphatase is missing?
Von Gierke’s
What is the location for fructose metabolism?
Liver
At what step does fructose enter glycolysis?
Triose phosphate step
What is the impact of high levels of fructose in the diet?
Increased fat production
