Glycolysis Flashcards
Another term for glycolysis?
Embden-Meyerhof-Parnas Pathway
What are the two stages and what steps do they span?
Energy investment stage (Steps 1-5)
Energy recovery stage (Steps 6-10)
Overall rxn and net ΔG?
glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 pyruvate + 2 NADH + 2 ATP + 2 H2O + 4H+
ΔG = -85 kJ/mol
Can metabolites escape the pathway?
No due to lack of transporters
In the synthesis of pyruvate, how do the following types treat pyruvate?
1. aerobic
2. hypoxic
3. hypoxic/anaerobic
aerobic: proceeds to TCA cycle (as acetyl) and oxidative phosphorylation
hypoxic: lactic acid fermentation
hypoxic/anaerobic: ethanol fermentation
What is bi-bi mechanism?
2 substrates produce 2 products
In step 1 of glycolysis, cofactor Mg2+ is needed. Why?
ATP will inhibit hexokinase instead of attacking D-glucose
Enzyme, substrate, and product of step 1?
hexokinase, glucose to glucose-6-phosphate (G6P) coupled with ATP to ADP + Pi
Enzyme, substrate, and product of step 2?
phosphoglucose isomerase, G6P to fructose-6-phosphate (F6P)
Enzyme, substrate, and product of step 3?
phosphofructosekinase-1 (PFK-1), F6P to fructose-1,6-biphosphate (FBP) coupled with ATP to ADP + Pi
Enzyme, substrate, and product of step 4?
fructose-1,6-biphosphate aldolase, FBP to Dihydroxyacetone phosphate (DHAP) + Glyceraldehyde-3-phosphate (G3P)
Enzyme, substrate, and product of step 5?
triosephosphate isomerase (TIM), DHAP to G3P
Enzyme, substrate, and product of step 6?
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), G3P to 1,3-biphosphoglycerate (1,3-BPG) coupled with NAD+ + Pi to NADH + H+
Enzyme, substrate, and product of step 7?
phosphoglycerate kinase (PGK), 1,3-BPG to 3-phosphoglycerate (3PG) coupled with ADP to ATP
Enzyme, substrate, and product of step 8?
Phosphoglycerate mutase, 3PG to 2-phosphoglycerate (2PG)
Enzyme, substrate, and product of step 9?
Enolase, 2PG to phosphoenol pyruvate (PEP)
Enzyme, substrate, and product of step 10?
Pyruvate Kinase, PEP to pyruvate (enol) and eventually to pyruvate (keto) coupled with ADP + H+ to ATP
In step 2 of glycolysis, why do we need to isomerize G6P to F6P?
Only F6P can yield 2 3C products. G6P yields 1 4C and 1 2C product.
Why is step 3 of glycolysis also known as the “first committed step”?
allosteric enhancers and inhibitors are present to enhance or inhibit structure of enzyme
Why does step 4 of glycolysis ensure the forward reaction to proceed?
fast removal of products from active site prevents reverse reaction. Very positive ΔG.
In step 5 of glycolysis, a ___________ is created to convert DHAP to G3P
enediol intermediate
In step 6, to convert G3P to 1,3-BPG, _________ and ________ must occur
phosphorylation and oxidation
Step 6 is the start of what stage?
Energy recovery stage
Step 7 is coupled with what step?
Step 6
Step 8 contains residues at at active site. What is/are this/these?
phospho-His and free His residues
What is the purpose of isomerization of 3PG to 2PG?
stability of anion products
Highly exergonic step of glycolysis that required the creation of other steps?
Step 9 is highly exergonic that is why step 7-8 is important for stability.
What is the final form of the product in step 10?
pyruvate keto form
Fates of the pyruvate molecule.
Ethanol fermentation
Lactic acid fermentation
TCA Cycle (as acetyl)
What pathway do the following autotrophs undergo?
1. Aerobes
2. Anaerobes
Aerobes : TCA Cycle as Anaerobes : fermentation
