13 - Glucose Metabolism Flashcards
what is gluconeogenesis?
pyruvate to glucose
using non carb sources
where does gluconeogenesis occur most and least?
more - liver [as lactate arrives and converted to glu]
less - kidney [glucose not needed]
what 3 things can act as precursors?
glycerol -> DHAP
lactate -> pyruvate
gluconeogenic amino acids
no. of reversible steps in glycolysis and gluconeogenesis?
gly - 7
glu - 12
what are the 3 non-reversible steps in glycolsis?
- pyruvate to phosenolpyruvate
- Fructose 1-6 Bisp to Fructose 6 Phosphate
- Glucose 6 phosp to Glucose
how does gluconeo convert these steps?
pyruvate to phosenolpyruvate
- converts pyruvate to OXALO
- pyruvate carboxylase
- oxolo to phosphoenolpyruvate
- phosphoenolpyruvate carboxykinase
Fructose 1-6 BP to Fructose 6 P
- by Fructose 1-6 bisphophotase
Glucose 6 Phosphate to Glucose
- glucose 6 phosphotase
how is lactaste converted to pyruvate?
by lactate dehydrogenase
NAD to NADH
in liver
how is glycerol converted to DHAP?
glycerol to Glycerol 3 P first
- Glycerol Kinase
G3P to DHAP
- glycerol phosphate dehydrogenase
pyruvate to oxaloacetate eq?
pyruvic acid + co2 + h2 = oxaloacetic acid + P
- pyruvate carboxylase
ATP
oxaloacetate to phosphoenolpyruvate eq?
Oxaloacteic Acid = Phosphoenolpyruvate
- phosphoenolpyruvate carboxykinase
fructose 1-6 BP to Fructose 6 phosphate eq?
F16BP = F6P
- fructose 1-6 bisphosphatse
glucose 6 phosphate to glucose?
glucose 6 phosphate = glucose
- glucose 6 phosphotase
reciprocal regulation: when will each pathway be activated?
energy needed
- glycol active
- gluco inactive
energy in excess
- glucon active
- gly inactive
what is the signalling molecule that causes reciprocal reg?
Fructose 2,6 Bisphosphate
which enzymes does Fructose 26 BP affect and how?
- stimulates phosphofructokinase
[converts fructose 6 phosphate to fructose 1 6 bisphosphate]
GLYCOL - inhibits fructose 1-6 bisphosphatase [reverse] GLUCONEO
what does a high level of PFK and Fructose 1-6bisphosphotase mean?
high PFK
- more glycolysis
high fructose 1-6 bisphosphotase
- more gluconeo
what synthesises and breaks signalling mol Fructose 2-6 bisphosphate?
PFK2 makes it
Fructose Bisphosphotase 2 [FBase2] breaks it
when F2-6BP is destroyed what does it become?
fructose 6 phosphate
what occurs in low blood glucose levels?
glucagon increases cAMP cascade activated Protein Kinase A phosphorylated FBPase 2 activated PFK2 inhibited so Fructose 26 BP broken down [decreases] Gluconeogensis
what occurs in high blood glucose levels?
insulin secreted Activate PFK2 Inhibit FBase2 Increase Fructose 2-6 BP Glycolysis
why is glycogen storage useful?
- high glucose distrupts osmotic balance
- not osmotically active
where is glycogen stored?
Liver
structure of gluyocgen?
branched
1-4 and 1-6 glycosidic bonds
how is glycogen broken down to give glucose?
glycogen
to
glucose 1 phosphate
[glycogen phosphorylase]
to
glucose 6 phosphate
[phosphoglucomutase]
