Metabolism 3 Flashcards
What are the 3 stages of metabolism?
- Digestion
- Cellular Metabolism 1
- Cellular Metabolism 2
Reaction 1 of Glycolysis
- Glucose —–> Glucose-6-phosphate
Enzyme: hexokinase (1 ATP used)
Reaction 2 of Glycolysis
- Glucose-6-phosphate ———-> Fructose-6-phosphate
Enzyme: Phosphoglucose isomerase
Reaction 3 of Glycolysis
- Fructose-6-phosphate ——-> Fructose-1,6-biphosphate
Enzyme: Phosphofructokinase
(1 ATP used)
Reaction 4 of Glycolysis
- Fructose-1,6-biphosphate ——-> Glyceraldehyde-3-phosphate (G3P) +dihydroxyacetone phosphate
Enzyme: Aldolase
Reaction 5 of Glycolysis
- Dihydroxyacetone phosphate ——> G3P
Enzyme: Triose phosphate isomerase
Reaction 6 of Glycolysis
- G3P ——> 1,3-biphosphoglycerate
Enzyme: G3P dehydrogenase
2x NADH generated (one for each G3P molecule)
Reaction 7 of Glycolysis
- 1,3-biphosphoglycerate —–> 3-phosphoglycerate
Enzyme: phosphoglycerate kinase
2x ATP produced
Reaction 8 of Glycolysis
- 3-phosphoglycerate ——-> 2-phosphoglycerate
Enzyme: phosphoglycerate mutase
Reaction 9 of Glycolysis
- 2-phosphoglycerate ——> phosphoenolpyruvate
Enzyme: Enolase
Dehydration type of reaction
Reaction 10 of Glycolysis
- Phosphoenolpyruvate ——> pyruvate
Enzyme: Pyruvate kinase
2x ATP generated
At the half way stage of glycolysis, what are the stats?
> 2 ATP used
2 moles of G3P produced
no ATP produced
What is substrate level phosphorylation?
ATP production via direct transfer of a high energy phosphate group from an immediate substrate in biochemical pathway to ADP.
Glycolysis is an example of substrate level phosphorylation.
What is oxidative phosphorylation?
ATP production using energy derived from transfer of e- in an e- transport system.
What are the 3 possible fates of Pyruvate?
- Alcoholic fermentation
- Lactate production
- Acetyl CoA generation
Explain alcoholic fermentation of pyruvate.
- Pyruvate to acetaldehyde (ethanal)
Enzyme: pyruvate decarboxylase
(H+ —-> CO2)
- Acetaldehyde —-> Ethanol
Enzyme: alcohol dehydrogenase
(NADH + H+ —-> NAD+)
Explain lactate generation.
Anaerobic process.
In conditions of oxygen deprivation, lactate production serves to regenerate NAD+ (essentially for glycolysis to continue)
Pyruvate ——–> Lactate
Enzyme: Lactate dehydrogenase
What molecule is a phosphate reservoir to phosphorylate ADP?
Creatine phosphate.
Muscle damage causes Creatine phosphate to leak into bloodstream
Creatine phosphate <===> creatine + ATP
Where does acetyl-CoA production occur?
In the mitochondria
Explain Acetyl-CoA generation.
Pyruvate + HS-CoA ——> Acetyl-CoA + CO2
Enzyme: Pyruvate Dehydrogenase Complex
NAD+ —-> NADH !!
What does the Pyruvate Dehydrogenase complex consist of?
3 Enzymes
5 co-factors
(some prosthetics are a PERMANENT part of the complex)
What are the 5 steps of the Pyruvate Dehydrogenase Complex?
- Decarboxylation of pyruvate. Gives hydroxyethyl TPP.
- Hydroxyethyl TPP oxidised and transferred to lipoamide. Gives acetyl-lipoamide.
- Acetyl group transferred to CoA. Gives Acetyl CoA.
- Oxidised lipoamide regenerated. Gives FADH2.
- Oxidised FAD regenerated. Gives NADH
Compare ATP generation in anaerobic and aerobic respiration.
Anaerobic = 2 ATP
Aerobic = 38 ATP
Which reaction in glycolysis produces NADH?
Reaction 6.
Which reactions in glycolysis produce ATP?
Reactions 7 and 10
