glucogenesis Flashcards
what is gluconeogenesis
- generates glucose from non carbohydrates like carbon, lactate, pyruvate, glycerol, glucogenic amino acids like Ala and glu
why do we need gluconeogenesis
- brain and CNS use it for energy
where does gluconeogenesis take place
90% in liver
10% in kidney
what is similar to Hexokinase, pdk-1 and Pk from glycolysis
glucose 6-phosphatase, fructose bisphosphatase, and pyruvate carboxylase and pep carboxykinase
how do you bypass pyruvate kinase
use pyruvate carboxylase and PEPCK (phosphoenolpyruvate carboxykinase)
what does Pyruvate carboxy do
catalyze atp
- depends on biotin conversion of pyruvate to oxaloacetae
where does pyruvate to oxalocetate happen
mitochondrial matrix
what does PEPCK do
- gtp to convert oxalo to phosphoenolpyruvate through phosphorylation
what is the energy cost of gluconeogenesis
- 2 atp
-2 gtp
2 atp
= 6 net atp equivalents
2 nadh
what is glucokinase
is it really hexokinase isozyme of glycolysis
what bypasses glucokinase
glucose 6 phosphatase
why is gluconeogenesis in the liver
huge buffer for glucose so glucokinase never achieves equilibrium
what is apart of gluconeogenesis but is not in the liver
pyruvate carboxylase and some PEP carboxylase they occur in the mito matrix
what is reciprocal regulation
- turn one one and the other off
what is the main control point in gluceogen
fructose 1,6 bisphosphatase
which control points take place @ the same time
pfk and fructose 1,6 causing a substrate cycle or hydrolysis of atp
what do substrate cycles do
- consume small amounts of atp but give a broadr range of control over metabolic rates
where is muscle lactate transferred to
the liver where it is turned into glucose via gluconeogen. or cori cycle
can gluconeogenesis start at lactate
yes, it is LDH in reverse direction
what is the energy cost of gluconeogen from lactate
6 atp (2 atp, 2 gtp, 2 atp)
2 nadh then -2 nadh so 0 nadh used
what is the cori cycle
- under anaerobic generate lactae
- muscle lactate is taken from bloodstream to liver
- gluconeogen starts w/ lactate dehydrogenase to convert lacctate to glucose where it is taken through bloodstream to muscle
ldh path
bloodstream –> liver–> bloodstream–. muscle - used for energy and stored as glycogen
