Pathway of Glucose Breakdown in a Cell:
 

Glycolysis:
- Glucose is first broken down into two molecules of pyruvate through a series of enzymatic reactions in the cytoplasm.
- This process is called glycolysis and does not require oxygen. It produces a small amount of ATP and NADH.

Pyruvate Oxidation:
- Pyruvate is then transported into the mitochondria where it is converted into Acetyl-CoA.
- This step generates NADH and releases carbon dioxide as a byproduct.

Citric Acid Cycle (Krebs Cycle):
- Acetyl-CoA enters the citric acid cycle, a series of reactions that further break down the molecules and release more NADH, FADH2, and ATP.
- Carbon dioxide is produced as a waste product in this cycle.

Electron Transport Chain:
- NADH and FADH2 produced in glycolysis, pyruvate oxidation, and the citric acid cycle donate their electrons to the electron transport chain in the mitochondria.
- This chain generates a large amount of ATP through oxidative phosphorylation by utilizing the energy released from the electron transfer.

Overall:
- The breakdown of glucose in a cell ultimately results in the production of a significant amount of ATP, which is the main source of energy for cellular functions.
- The entire process involves multiple steps and different cellular compartments to efficiently extract energy from glucose molecules.