Glycolysis Flashcards
Where in the cell does glycolysis occur?
Cytosol
How many steps are in the preparatory phase and how much ATP does this phase produce
6 reactions, net loss of 2 ATP
How much ATP does glycolysis produce overall?
5-7 ATP per glucose (2ATP and 2NADH)
What are the five fates of pyruvate?
1) Ethanol
2) Lactate
3) Acetyl CoA
4) Oxaloacetate
5) Alanine
Describe the important role of anaerobic glycolysis?
The fermentation of Pyruvate to L-Lactate is catalyzed by lactate dehydrogenase, which helps in the regeneration of NAD+, which is vital to step 6 in glycolysis, which without aerobic respiration is the body’s only source of energy.
What is the relationship between glycolysis and cancer?
In cancerous cells, glycolysis can occur up to 10x faster, which can be labeled with isotopically labeled glucose followed by PET scanning (Diagnosis)
What is the Warburg hypothesis?
most cancer cells produce energy via anaerobic glycolysis rather than the oxidation of pyruvate in the mitochondria.
Describe the metabolic fate of lactate produced in the muscle and how this is linked to metabolism in the liver
Lactate produced in muscles will enter into the Cori Cycle. The lactate will become blood lactate that, when entering the liver will convert back to lactate in the liver. During recovery, ATP can be used to convert the lactate back to glucose via gluconeogenesis, which will enter the blood stream and can be transported back to the muscle cells, where if needed, the cycle can begin again.
What are the steps in the preparatory phase of glycolysis and what are the enzymes and cofactors needed for these reactions?
Reaction 1
Glucose phosphorylated by hexokinase with the cofactor Mg2+ and ATP to produce Glucose-6-phosphate. This reaction is irreversible.
Reaction 2
Glucose-6-phosphate is isomerised by phosphohexose isomerase with the cofactor Mg2+ to produce Fructose-6-phosphate. This reaction is reversable, and this enzyme and cofactor will catalyse both directions.
Reaction 3
Fructose-6-phosphate is converted to Fructose-1,6-bisphosphate by the enzyme phosphofructokinase-1 and a cofactor Mg2+ and ATP. This is the second irreversible step in glycolysis.
Reaction 4
This reaction is the cleavage (Splitting in half) of Fructose-1,6-bisphosphate by the enzyme aldolase into Dihydroxyacetone phosphate and Glyceraldehyde-3-phosphate. This step is reversible, and both directions are catalyzed by aldolase.
Reaction 5
This is the isomerisation of Dihydroxyacetone phosphate to Glyceraldehyde-3-phosphate by the enzyme Triose Phosphate Isomerase. This again is a reversible reaction.
What are the steps in the pay-off phase of glycolysis and what are the enzymes and cofactors needed for these reactions?
Reaction 6
Glyceraldehyde-3-phosphate oxidised to 1,3 Bisphosphoglycerate using the enzyme Glyceraldehyde-3-phosphate dehydrogenase and the turnover of NAD+.
Reaction 7
1,3-Bisphosphoglycerate converted to 3-phosphoglycerate when catalysed by phosphoglycerate kinase, which has to be used in conjunction with ADP. This reaction also uses the cofactor Mg2+ and requires protein motion. This is the first ATP generating step.
Reaction 8
Phosphoglycerate mutase with cofactor Mg2+ converts 3-Phosphoglycerate to 2-Phosphoglycerate. Preparing the molecule for phosphate transfer to ATP.
Reaction 9
2-Phosphoglycerate dehydrated to Phosphoenolpyruvate be enolase, which is a Mg2+ dependant enzyme. This reaction also produces H2O.
Reaction 10
Conversion of Phosphoenolpyruvate to pyruvate through the production of ATP. This is catalysed by the enzyme pyruvate kinase, which has Mg2+/K+ cofactors.
