Energy generation: Third stage of glycolysis Flashcards
What does the third STAGE of glycolysis involve?
Generates energy in the form of production of ATP\
Core of glycolysis
Results: Oxidation of the sugars, coupled to reduction of NAD+ to NADH
2 steps where ATP is produced= Using a phosphorylated sugar with a high phosphoryl group transfer potential to phosphorylate ADP
What is the first step of the third stage of glycolysis?
Glyceraldehyde 3-phophate (GAP) + NAD+ + Pi —> 1,3-bisphosphoglycerate + NADH + H+
Catalysed by glyceraldhyde 3-phosphae dehydrogenase
GAP is oxidised
Why is this step so important?
Generates a compound containing a phosphoryl group with a high transfer potential, WITHOUT ATP
This new high energy phosphate bond comes from the oxidation of the aldehyde group of the GAP
This phosphorylation step by itself would have a large +veΔG BUT the favourable redox reaction is used to drive the unfavourable reaction
What is the second step in the third stage of glycolysis?
1,3-bipshophoglycerate + ADP 3-phosphoglycerate + ATP
FIRST STEP IN ATP PRODUCTION
The phosphoryl group attached to the carboxylic acid group has a high transfer potential and can phosphorylate ADP in thermodynamically favoured reaction
Catalysed by phosoglycerate kinase
Energetically favourable to go in forward direction= ATP production
1,3-BP is better donor of phosphate than ATP
What is the third step in the third stage of glycolysis?
2 steps to this:
1) 3-phosphate 2-phosphoglycerate
Catalysed by: Phosphoglycerate mutase
Movement of phosphate group to a different carbon atom within the same molecule
2) 2-phosphoglycerate Phosphenolpyruvate + H2O
Catalysed by: Enolase
Dehydration to form C=C bond
Product: Phosphenolpyruvate is very good donor of phosphate as it is energetically favourable
What is the fourth step in the third stage of glycolysis?
Phosphoenolpyruvate + ADP + H+ —-> Pyruvate + ATP
Catalysed by: Pyruvate kinase
