Pentose Phosphate And Gluconeogenesis Flashcards
What is catabolism?
the breakdown of complex molecules in living
organisms to form simpler ones, together with the
release of energy; destructive metabolism
What is anabolism?
the synthesis of complex molecules in living
organisms from simpler ones together with the
storage of energy; constructive metabolism.
What is the primary function of the Pentose Phosphate Pathway (PPP)?
To produce NADPH for reductive biosynthesis (e.g., fatty acid synthesis) and ribose-5-phosphate for nucleic acid synthesis.
What are the two branches of the Pentose Phosphate Pathway?
The oxidative branch, which generates NADPH, and the non-oxidative branch, which interconverts sugars.
What is the key regulatory enzyme in the Pentose Phosphate Pathway?
Glucose-6-phosphate dehydrogenase, which is inhibited by high NADPH levels.
What is gluconeogenesis?
The process by which glucose is synthesized from non-carbohydrate precursors like lactate, amino acids, and glycerol.
Why is gluconeogenesis not simply the reverse of glycolysis?
It requires unique enzymes to bypass the irreversible steps of glycolysis, consuming more energy in the form of ATP and GTP.
What are the main substrates for gluconeogenesis?
Lactate, amino acids (like alanine), and glycerol.
How are glycolysis and gluconeogenesis regulated?
They are reciprocally regulated to avoid energy waste, with glycolysis active when energy is needed and gluconeogenesis active when glucose is needed.
What role does insulin play in gluconeogenesis?
Insulin inhibits gluconeogenesis, reducing the expression of enzymes like phosphoenolpyruvate carboxykinase and glucose-6-phosphatase.
What does glucagon do in gluconeogenesis?
Glucagon stimulates gluconeogenesis, particularly in the liver, by activating pathways that promote glucose production.
How does the Cori cycle help during anaerobic conditions in muscles?
It recycles lactate produced in muscles back to glucose in the liver, reducing the metabolic burden on muscles.
