SESSION 12

Location of Glycolysis: Glycolysis occurs in the cytosol, breaking glucose into two pyruvate molecules, yielding 2 ATP and 2 NADH.

Regulation of Glycolysis: The enzyme phosphofructokinase regulates glycolysis through feedback inhibition. High ATP levels inhibit its activity, slowing the pathway.

Reactions in the Citric Acid Cycle: Acetyl CoA enters the cycle in the mitochondrial matrix, producing 6 NADH, 2 FADH2, and 2 ATP per glucose, with CO2 as a byproduct.

High-Energy Intermediates and Regulation: NADH and FADH2 store energy for the Electron Transport Chain (ETC). The cycle is regulated by ATP and NADH levels via feedback inhibition.

Energy Use in ETC: Electrons from NADH and FADH2 pass through the ETC, releasing energy to pump protons and create an electrochemical gradient.

Oxidative Phosphorylation and ATP Synthase: Protons flow through ATP synthase, using the gradient's energy to convert ADP to ATP.

Oxygen's Role: Oxygen acts as the final electron acceptor in the ETC. Without it, cells switch to less efficient fermentation.

Fermentation vs. Cellular Respiration: Fermentation yields 2 ATP per glucose, while cellular respiration generates 29 ATP, making respiration much more efficient.

Photosynthesis vs. Cellular Respiration:

• Photosynthesis stores energy in glucose molecules (endergonic).

• Cellular respiration releases energy from glucose to make ATP (exergonic)