Gluconeogenesis2 Flashcards
What is a biotin dependent mitochondrial enzyme?
Pyruvate carboxylase
What enzyme converts glucose 6 phosphate to glucose?
G6Pase
What amino acids don’t participate in gluconeogenesis?
Leucine and lysine
What are the possible ways of amino acid conversion to glucose?
They either form the pyruvate or CAC intermediates which ultimately form glucose
How is glycerol from fat converted to glucose?
First the fat is broken down then the glycerol is phosphorylated by glycerol kinase enzyme and after this the intermediate DHAP is formed that goes into the gluconeogenic pathway.
How is glucose formed from propionate compounds?
First the compound is broken down to propionyl CoA -> methyl malonyl CoA -> succinyl CoA -> enters gluconeogenic pathway
What is the glucose- alanine cycle?
During starvation, amino acid (muscle) is transaminated to leucine and then its transported to the liver where it is used in gluconeogenesis.
What important enzymes for glucose production are absent in the muscle tissue?
G6P and F1,6-BP
What happens in the Cori cycle?
Vigoursly active muscles tissues produce lactate (reduced product). It’s not processed in the tissue due to lack of essential enzymes, hence transported to the liver where it is oxidized to glucose. This glucose is then returned to the muscle tissue. The whole cycle is termed as Cori cycle.
Both amino acids and alanine form the pyruvate, what are the other intermediates before glucose is synthesized?
Pyruvate -> G6P -> Glucose
How is gluconeogenesis regulated?
Two ways, glucagon hormone and substrate level regulation
How does glucagon regulates the gluconeogenic pathway?
It inactivates the activity of Pyruvate kinase and thus reducing the synthesis of pyruvate. At substrate level, F2,6bisphosphate conc is reduced. PFkinase is inhibited and F1,6-BP is enhance, which promotes gluconeogenesis.
What is the significance of acetyl CoA with respect to gluconeogenesis?
Enhancement and pyruvate carboxylase activation
What is the effect of alcohol on gluconeogenesis?
Restrains the process, interferes with pyruvate and oxaloacetate availability, consumes NAD+ hence NADH accumulates due to which the intermediates become unavailable.
What is the prime reason behind animals inability to convert fat to glucose?
- It produces acetyl CoA which cannot be converted to glucose, and absence of glyoxylate cycle
