Glycolysis 0.0 / 5 ? AllUniversityNone Created by: Megan PotterCreated on: 12-05-13 10:08 What are the two phases of glycolysis? Preparatory phase and pay-off phase 1 of 34 What is the first stage? Phosphorylation of glucose 2 of 34 Which enzyme? Hexokinase 3 of 34 How? Glucose is activated by phosphorylation at C-6, giving glucose 6-phosphate. Hexokinase requires Mg2+. 4 of 34 What is the second stage? Conversion of glucose 6-phosphate to fructose 6-phosphate 5 of 34 Which enzyme? Phosphohexose isomerase 6 of 34 How? reversible isomerization of an aldose to a ketose. A critical step - rearrangement of the carbonyl and hydroxyl groups at C-1 and C-2. 7 of 34 What is the third stage? Phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate 8 of 34 Which enzyme? Phosphofructokinase-1 (PFK-1) 9 of 34 How? Essentially irrevesible step. Enzyme is inhibited when there are ample amounts of ATP in the cell, and stimulated when the supply is depleted 10 of 34 What is the fourth stage? Cleavage of fructose 1,6-bisphosphate 11 of 34 Which enzyme? Fructose 1,6-bisphosphate aldolase (aldolase) 12 of 34 How? A reversible aldol condensation, yielding two triose phosphates - glyceraldehyde 3-phosphate and dihydroxyacetone phosphate 13 of 34 What is the fifth stage? Interconversion of the triose phosphates 14 of 34 Which enzyme? Triose phosphate isomerase 15 of 34 How? Dihydroxyacetone phosphate must be converted into glyceraldehyde 3-phosphate before it can be used in subsequent steps 16 of 34 What is the sixth stage? Oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate 17 of 34 Which enzyme? Glyceraldehyde 3-phosphate dehydrogenase 18 of 34 How? Oxidation. First of two energy conserving steps 19 of 34 What is the seventh stage? Phosphoryl transfer from 1,3-bisphosphoglycerate to ADP 20 of 34 Which enzyme? Phosphoglycerate kinase 21 of 34 How? Transfers the phosphoryl group from the carboxyl group of 1,3-bisphosphoglycerate to ADP. Forms ATP and 3-phosphoglycerate 22 of 34 What is the eighth stage? Conversion of 3-phosphoglycerate to 2-phosphoglycerate 23 of 34 Which enzyme? Phosphoglycerate mutase 24 of 34 How? A reversible shift of the phosphoryl group between C-2 and C-3 of glycerate. Mg2+ is essential 25 of 34 What is the ninth stage? Dehydration of 2-phosphoglycerate to phosphoenolpyruvate 26 of 34 Which enzyme? Enolase 27 of 34 How? Reversible removal of a water molecule from 2-phophoglycerate. Requires Mg2+ to stabilise an enolic intermediate 28 of 34 What is the tenth stage? Transfer of the phosphoryl group from phosphoenolpyruvate to ADP 29 of 34 Which enzyme? Pyruvate kinase 30 of 34 How? Substate-level phosphorylation, requires K+ and Mg2+ or Mn2+. Forms Pyruvate. 31 of 34 How many molecules of pyruvate can be made from one glucose molecule? 2 32 of 34 What is the net gain of ATP? 2 - four are created in the pay-off phase, but two are used in the preparatory phase. 33 of 34 How many NADH are produced? 2 34 of 34
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