Lecture Set 16 Flashcards
Where does glycolysis occur? Does it require molecular oxygen? Why or why not?
Occurs in the cytosol. Doesn’t need oxygen because NADH can be oxidized to NAD+ by various enzymes and production of lactate from pyruvate in anaerobic conditions
List the 10 steps of glycolysis and the enzymes required
1) Glucose + ATP + Mg2+ –> Glucose-6-phosphate + ADP, hexose kinase (IRREVERSIBLE)
2) Glucose-6-phosphate + Mg2+ –> Fructose-6-phosphate, phosphoglucose isomerase
3) Fructose-6-phosphate + ATP + Mg2+ –> Fructose-1,6-bisphosphate + ADP, phosphofructokinase-1 (IRREVERSIBLE)
4) Fructose-1,6-Bisphosphate –> dihydroxyacetone phosphate + glyceraldehyde-3-phosphate, aldolase
5) dihydroxyacetone phosphate –> glyceraldehyde-3-phosphate, triose phosphate isomerase
6) Glyceraldehyde-3-phosphate + Pi + NAD+ –> 1,3-Bisphosphoglycerate + NADH, glyceraldehyde-3-phosphate dehydrogenase
7) 1,3-Bisphosphoglycerate + ADP + Mg2+ –> 3-phosphogylcerate + ATP, phosphoglycerate kinase
8) 3-phosphoglycerate + Mg2+ –> 2-phosphoglycerate, phosphoglycerate mutase
9) 2-phosphoglycerate –> phosphoenolpyruvate + H2O, enolase
10) phosphoenolpyruvate + K+ + Mg2+ + ADP –> pyruvate + ATP, pyruvate kinase
Describe the 3 metabolic fates of pyruvate
aerobic conditions: reacts with pyruvate dehydrogenase to release CO2, turns into acetyl-CoA. NAD+ gets reduced to NADH, later oxidized by molecular oxygen
anaerobic conditions, animals: reacts with lactate dehyrogenase to turn into lactate
anaerobic conditions, plants: reacts with pyruvate carboxylase to release CO2, turn into acetaldehyde, then reacts with alcohol dehyrogenase to turn into ethanol
In anaerobic conditions, NADH gets oxidized back to NAD+ through the reduction of pyruvate, this NAD+ goes back and supplies the NAD+ for Gly6
Describe what a high-energy bond really is
No such thing as a high energy bond, what really happens is that there is a large difference in free energy between reactants and products
