The chemical process by which sugar is oxidized in the human body is called cellular respiration. It's a complex series of reactions that occur in the cells to break down glucose (sugar) and release energy in the form of ATP (adenosine triphosphate).

Here's a simplified overview:

1. Glycolysis:

- Glucose enters the cell and is broken down into pyruvate.

- This process occurs in the cytoplasm and doesn't require oxygen.

- It produces a small amount of ATP.

2. Transition Reaction:

- Pyruvate is converted into acetyl-CoA, which enters the mitochondria.

3. Krebs Cycle (Citric Acid Cycle):

- Acetyl-CoA enters the Krebs cycle, a series of reactions that produce electron carriers (NADH and FADH2) and some ATP.

4. Electron Transport Chain:

- The electron carriers (NADH and FADH2) donate electrons to the electron transport chain, a series of protein complexes embedded in the mitochondrial membrane.

- As electrons move through the chain, energy is released and used to pump protons across the membrane, creating a proton gradient.

- This gradient drives the synthesis of ATP, the primary energy currency of the cell.

Overall Equation:

C6H12O6 (glucose) + 6O2 (oxygen) → 6CO2 (carbon dioxide) + 6H2O (water) + energy (ATP)

Key Points:

- Oxidation: Sugar (glucose) is oxidized, meaning it loses electrons.

- Oxygen: Oxygen is the final electron acceptor in the electron transport chain, ultimately being reduced to form water.

- ATP: The energy released during oxidation is used to produce ATP, which is essential for cellular functions.

Note: This is a simplified explanation. Cellular respiration is a highly complex and regulated process involving many enzymes and cofactors.