Final answer:
In cellular fermentation, glucose is the sugar that is broken down, CO₂ is a byproduct, and the process occurs in the absence of oxygen. The balanced chemical equation for the fermentation of glucose by yeast is C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Unlike aerobic respiration, fermentation does not yield large amounts of ATP.
Step-by-step explanation:
The roles of glucose, CO₂, and oxygen in cellular fermentation are distinct. Glucose is the primary fuel that undergoes fermentation and is broken down into pyruvate during glycolysis. In the absence of oxygen, the further breakdown of glucose stops at this stage because oxygen is not present to accept electrons in the electron transport chain.
Instead, fermentation takes an alternative route to regenerate NAD, a vital molecule for glycolysis to continue. In the process of alcohol fermentation by yeast cells, glucose is converted into ethanol and CO₂. This transformation is summarized by the balanced chemical equation:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
In this equation, one molecule of glucose (C₆H₁₂O₆) is fermented to produce two molecules of ethanol (C₂H₅OH) and two molecules of carbon dioxide (CO₂). Oxygen is not required for fermentation to take place, and this process allows cells to continue to produce ATP albeit much less efficiently than aerobic respiration, which requires oxygen and yields more ATP.