identify the reactions that generate reducing equivalents that are oxidized in the mitochondrial electron transport chain to yield ATP.

The reactions that generate reducing equivalents that are oxidized in the mitochondrial electron transport chain to yield ATP are:

1. Glycolysis: This is the first step in the breakdown of glucose to extract energy for cellular metabolism. It produces two molecules of pyruvate, two molecules of NADH (the reducing equivalent), and a net gain of two ATP molecules.

2. Pyruvate Decarboxylation: Each pyruvate is decarboxylated to form one molecule of CO2 and one molecule of acetyl CoA. This reaction also produces one NADH molecule.

3. Citric Acid Cycle (Krebs Cycle): Each acetyl CoA enters the citric acid cycle, where it is oxidized to CO2. This process generates three molecules of NADH, one FADH2 (another reducing equivalent), and one ATP.

4. Beta-Oxidation: This is the process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are used by the electron transport chain.

These reducing equivalents (NADH and FADH2) produced in the above reactions are then oxidized in the electron transport chain, a series of protein complexes located in the inner mitochondrial membrane. As these complexes are reduced and then re-oxidized, they pump protons (H+ ions) across the membrane, creating a proton gradient. This gradient is used by ATP synthase to generate ATP, the cell's main source of energy.