Carbohydrates 3 Flashcards
How much energy is gained from glycolysis?
Net gain of 2 ATP and one NADH
First step
Phosphorylation of glucose to glucose-6-phosphate. This uses one ATP and is irreversible. Catalysed by hexokinase.
Second step
Glucose-6-phosphate is converted to fructose-6-phosphate by phosphohexose isomerase
Third step
Fructose-6-phosphate is phosphorylated to fructose-1,6-bisphosphate by phosphofructokinase-1. This makes the molecule easier to cleave and is the first committed step of glycolysis. It uses an ATP.
Fourth step
Fructose-1,6-bisphosphate is cleaved to form two triose sugars by aldolase. The reaction is readily reversible in cellular conditions.
Fifth step
One of the triose sugars that isn’t already ready (dihydroxyacetone phosphate) is converted to glyeraldehyde-3-phosphate by triose phosphate isomerase.
Sixth step
Glyceraldehyde-3-phosphate is oxidised to 1,3-bisphosphoglycerate by a dehydrogenase (substrate Name prefix). Two NADH are produced.
Seventh step
A phosphate is transferred from 1,3-bisphosphoglycerate to ADP to make 2 ATP in a substrate Level phosphorylation with the enzyme phosphoglycerate kinase.
Eighth step
3-phosphoglycerate is converted to 2-phosphoglycerate by phosphoglycerate mutase.
Ninth step
2-phosphoglycerate is dehydrated to phosphoenolpyruvate by enolase.
Tenth step
Phosphoenolpyruvate has a phosphate removed to ADP to make two ATP by pyruvate kinase. Pyruvate is formed.
How is more NAD+ produced in glycolysis to keep the process going?
Pyruvate is reduced to lactate in anaerobic conditions which uses NADH to produce NAD+ by lactate dehydrogenase.
What is the cori cycle?
It involves muscle breaking down pyruvate to lactate which is then taken up by the liver and made back into glucose by gluconeogenesis.
How and when does pyruvate convert to acetyl CoA?
When there is oxygen present it is oxidised to form acetyl CoA which enters the CAC. This occurs within the mitochondria.
