Gluconeogenesis Flashcards
Which glycolysis steps are bypassed in gluconeogenesis?
Steps involving the enzymes pyruvate kinase, phosphofructokinase, and hexokinase.
Which tissues perform gluconeogenesis?
The liver, and to a lesser extent the kidneys.
What does gluconeogenesis do?
Turns lactate from exercising muscles back into glucose.
How are glycolysis and gluconeogenesis regulated in the cell?
By the energy needs of the cell, so that when glycolysis is occurring, gluconeogenesis is not and vise versa.
How is the interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate regulated?
AMP activates and the enzyme PFK-1 (forward reaction in glycolysis) and AMP inhibits FBPase (enzyme responsible for the reverse reaction involved in gluconeogenesis).
So low energy in the cell stimulates the forward/glycolysis reaction and turns off FBPase, while high energy in the cell stimulates the reverse reaction/glucneogenesis and turns off PFK1.
What are the two ways the interconversion of phosphoenolpyruvate and pyruvate regulated?
By AcetylCoA - if AcetylCoA is elevated, then oxaloacetate will start the process of becoming PEP and therefore gluconeogenesis rather than binding with AcetylCoA to form citrate and start the TCA.
Gluconeogenesis is stimulated by hormones glucocorticoids and glucagon, which stimulate the transcription of the genes that make PEP-carboxylase.
Glycolysis is stimulated by insulin, which down-regulates the transcription of PEP-carboxylase.
What is the Cori Cycle?
Transport of lactate from muscles to the liver to be made into glucose via gluconeogenesis, and delivered back to muscle cells.
Van Gierke’s disease
Glycogen storage disease type I (GSD I) - results from a deficiency in glucose 6-phosphatase, an enzyme of gluconeogenesis (can’t turn G6P into glucose).
What is a ketogenic amino acid?
ketogenic amino acids are converted into Acetyl CoA - precursors for fatty acids which are then stored in adipose tissue.
Which amino acids are exclusively ketogenic?
Lysine and Leucine.
What is a glycogenic amino acid?
precursor to pyruvate or oxaloacetate for storage as glycogen or production of glucose.
