MP3 - Glycolysis, Pyruvate Oxidation, Krebs Cycle

What is the overall process of Glycolysis?

The breakdown of glucose from a 6-C molecule to two 3-C pyruvates.

How many enzyme-catalyzed reactions are in Glycolysis?

10

What are the two phases of Glycolysis?

Energy investment phase and energy payoff phase.

What are the inputs of Glycolysis?

Glucose and 2 ATP.  

What are the outputs of Glycolysis?

2 net ATP, 2 NADH, and 2 pyruvate molecules.  

Does pyruvate oxidation directly produce ATP?

No.  

Where does pyruvate oxidation occur?

In the mitochondrial matrix.  

What are the products of pyruvate oxidation?

1 NADH and 1 acetyl-CoA per pyruvate.  

Where does the Krebs cycle occur?

In the mitochondrial matrix.

How many enzyme-catalyzed reactions are in the Krebs cycle?

Eight.

What are the products of the Krebs cycle per acetyl-CoA?

3 NADH, 1 FADH2, and 1 ATP.  

What is the total ATP produced from Glycolysis and the Krebs cycle?

4 ATP.

Describe the energy investment phase of glycolysis.

• Phosphorylation of glucose to glucose-6-phosphate.

• Isomerization of glucose-6-phosphate to fructose-6-phosphate.

• Phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.

Explain the payoff phase of glycolysis. Detail the steps that lead to ATP and NADH production.

• Hydrolysis of fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP).

• Conversion of DHAP to G3P.

• Oxidation of G3P to 1,3-bisphosphoglycerate, producing NADH.

• Substrate-level phosphorylation to produce ATP and 3-phosphoglycerate.

• Conversion of 3-phosphoglycerate to phosphoenolpyruvate (PEP).

• Substrate-level phosphorylation to produce ATP and pyruvate.

What are the final products of glycolysis, and how much ATP and NADH are generated?

• 2 pyruvate molecules

• 2 net ATP molecules

• 2 NADH molecules

Describe the process of pyruvate oxidation. Where does it occur, and what are the products?

• Occurs in the mitochondrial matrix.

• Pyruvate is converted to acetyl-CoA.

• 1 NADH is produced per pyruvate.

Outline the key steps and products of the Krebs cycle. Include the inputs and outputs of the cycle.

• Acetyl-CoA combines with oxaloacetate to form citrate.

• Series of enzymatic reactions that regenerate oxaloacetate.

• Production of 3 NADH, 1 FADH2, and 1 ATP per acetyl-CoA.

For each glucose molecule, how many NADH, FADH2, and ATP molecules are produced from glycolysis, pyruvate oxidation, and the Krebs cycle combined?

• 2 NADH from glycolysis

• 2 NADH from pyruvate oxidation

• 6 NADH from Krebs cycle

• 2 FADH2 from Krebs cycle

• 2 ATP from glycolysis (net)

• 2 ATP from Krebs cycle