What can glucose be synthesised from in gluconeogenesis?
Non-carbohydrate precursors and simple 3C and 4C precursors
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What is a problem with gluconeogenesis?
It is an irreversible reaction of glycolysis
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How many bypasses are there in gluconeogenesis and what are they?
3, Bypass 1 (pyruvate to phosphoenolpyruvate), bypass 2 (fru-1,6-bisphophate to Fru-6P) and bypass 3 (Glucose-6P to glucose)
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Describe bypass 1
2 step process- step 1, carboxylation reaction (Pyruvate converted to oxaloacetate), step 2, decarboxylation and phosphorylation reaction (Oxaloacetate converted to PEP)
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Describe the first step
Biotin is bound to the enzyme (prosthetic group), a carboxyl group from biotin is transferred to pyruvate, 1 ATP per pyruvate molecule, (Enzyme: Pyruvate carboxylase), product: oxaloacetate
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Describe the second step
1 GTP for every oxaloacetate, decarboxylation and phosphorylation of oxaloacetate, (Enzyme: phosphoenolpyruvate carboxykinase)
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Describe the second bypass
Hydrolysis reaction, ADP is not phosphorylated into ATP, phosphate released (Enzyme: Fructose-1,6-bisphosphotase)
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Describe the third bypass
Hydrolysis reaction, ADP is not phosphorylated into ATP, phosphate released, (Enzyme: Glucose-6-phosphotase)
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What is the glyoxylate pathway?
Part of the TCA cycle, bacteria and germinating oil seeds use this, by-pass oxidative decarboxylation reactions of the TCA cycle, no carbon atoms from acetate/ acetyl CoA are lost
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Describe the 2 processes of the glyoxylate pathway
1) Isocitrate lyase cleaves isocitrate to become succinate and glyoxylate, 2) Malate synthase produces malate from glyoxylate and acetyl CoA
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Other cards in this set
Card 2
Front
What is a problem with gluconeogenesis?
Back
It is an irreversible reaction of glycolysis
Card 3
Front
How many bypasses are there in gluconeogenesis and what are they?
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