BGM1002/L21 Glycolysis Flashcards
Name the 3 major pathways in glucose oxidation.
Glycolysis
Citric Acid cycle
Oxidative Phosphorylation
What is glycolysis?
Conversion of glucose to pyruvate
Why is glycolysis important?
Generates anaerobic energy
Name the 3 stages of glycolysis.
Investment/priming
Splitting
Energy conservation/yield
What are the reactants and products in the investment/priming stage of glycolysis?
Glucose -> Fructose-1,6-bisphosphate
What are the reactants and products of the splitting stage of glycolysis?
Fructose-1,6-bisphosphate -> Glyceraldehyde-3-phosphate
What are the reactants and products of the energy conservation/yield stage of glycolysis?
Glyceraldehyde-3-phosphate -> pyruvate
What else is used in the investment stage, other than glucose?
ATP
Name the 2 reaction intermediates in the investment stage.
Glucose-6-phosphate
Fructose-6-phosphate
How is glucose-6-phosphate trapped inside cells?
It is repelled by the cell membrane
Which enzyme adds a phosphate group to a pyranose sugar?
Hexokinase
Why is it useful to convert glucose to glucose-6-phosphate?
Glucose-6-phosphate becomes trapped inside cells
Name the 3 steps of the investment stage of glycolysis.
- Phosphate added to pentose sugar
- 6-membered ring converted to 5-membered ring (isomerisation)
- Phosphorylation (again)
Why is the second phosphoanhydride bond in ATP protected from hydrolysis?
Mg2+ between alpha and beta phosphate group
In step 2 of investment, what kind of molecule is the reactant and product?
Aldopyranose - ketofuranose
Why is the 6-membered ring converted to a 5-membered ring in step 2 of investment?
5-membered rings are less stable than 6-membered rings
What enzyme is involved in adding a phosphate group to fructose-6-phosphate in step 3 of investment?
Phosphofructokinase
What is the overall role of the splitting phase of glycolysis?
6-carbon molecule into 2x 3-carbon molecules
What features does fructose-1,6-bisphosphate have contributing to lack of stability? (2)
Line of symmetry
Two repelling phosphate groups
What is the role of aldolase in glycolysis? (Step 4)
Breakdown of fructose-1,6-bisphosphate into dihydroxyacetone-phosphate and glyceraldehyde-3-phosphate
What is the role of triosephosphate isomerase in glycolysis? (Step 4)
Converting dihydroxyacetone-phosphate into glyceraldehyde-3-phosphate
What enzymes are involved in step 4 of glycolysis (splitting)? (2)
Aldolase
Triosephosphate isomerase
What is fructose-1,6-bisphosphate split into during step 4 of glycolysis?
Dihydroxyacetone-phosphate
Glyceraldehyde-3-phosphate
What is the product of the splitting phase of glycolysis?
2x Glyceraldehyde-3-phosphate
How many steps are involved in the yield stage of glycolysis?
5
What enzyme adds a free phosphate to glyceraldehyde-3-phosphate in step 6 of glycolysis?
Glyceraldehyde-3-phosphate dehydrogenase
Via NAD+
What enzyme conducts substrate level phosphorylation in step 7 of glycolysis?
Phosphoglycerate kinase
What enzyme transfers phosphate to the central carbon in step 8 of glycolysis?
Phosphoglycerate mutase
What enzyme removes water from 2-phosphoglycerate in step 9 of glycolysis?
Enolase
What enzyme removes the phosphate group from phosphoenolpyruvate in step 10 of glycolysis?
Pyruvate kinase
Which 2 steps of glycolysis yield ATP?
Step 7 and 10
Name the 6 molecules involved in the yield stage of glycolysis.
Glyceraldehyde-3-phosphate
1,3-biphosphoglycerate
3-phosphoglycerate
2-phosphoglycerate
Phosphoenolpyruvate
How many ATPs are gained from glycolysis of 1 molecule of glucose?
2
Which 2 steps yield ATP in glycolysis?
1,3-biphosphoglycerate -> 3-phosphoglycerate (7)
Phosphoenolpyruvate -> pyruvate (10)
What occurs during step 6 of glycolysis (yield stage)?
Gaining of a free phosphate by NAD+ via Glyceraldehyde-3-phosphate dehydrogenase
What occurs during step 7 of glycolysis (yield stage)?
Production of first ATP by substrate level phosphorylation via phosphoglycerate kinase
What occurs during step 8 of glycolysis (yield stage)?
Transfer of phosphate to central carbon via phosphoglycerate mutase
What occurs during step 9 of glycolysis (yield stage)?
Increased energy potential of molecule by removal of water via enolase
What occurs during step 10 of glycolysis (yield stage)?
Second energy producing reaction
How many ATP are invested in stage 1 of glycolysis?
2
How many ATP are generated in stage 3 of glycolysis?
4
A supply of what other molecule is required for glycolysis?
NAD+
NADH produced
What is the net gain of ATP per glucose molecule?
2
