Aerobic vs. Anaerobic Respiration

The notes in this series on cellular microbiology are all created using ChatGpt. So do cross check and verify on your own too

The difference between yeast and bacteria in terms of energy manufacturing relates to whether they use aerobic (with oxygen) or anaerobic (without oxygen) processes. Here’s a simple breakdown:

1. Aerobic Respiration (with oxygen):

• Process: When oxygen is available, yeast cells use aerobic respiration to generate energy.

• How it works:

Yeast breaks down glucose in the mitochondria, releasing ATP (energy), carbon dioxide (CO₂), and water (H₂O).

This process is highly efficient and produces up to 36-38 molecules of ATP per glucose molecule.

• Example: When yeast is used in baking bread, it uses aerobic respiration until oxygen is depleted.

2. Anaerobic Respiration (without oxygen):

• Process: In the absence of oxygen, yeast switches to anaerobic respiration or fermentation.

• How it works:

Instead of going through the mitochondria, yeast ferments glucose in the cytoplasm, producing ethanol (alcohol) and carbon dioxide (CO₂).

This process is much less efficient, yielding only 2 molecules of ATP per glucose molecule.

• Example: When yeast ferments in brewing beer or making wine, it uses anaerobic respiration to produce alcohol.

Bacteria: Aerobic vs. Anaerobic Respiration

1. Aerobic Respiration (with oxygen):

• Process: Some bacteria, like those that live in oxygen-rich environments (e.g., in soils or our bodies), use aerobic respiration.

• How it works:

Just like in yeast, glucose is broken down using oxygen, producing ATP, CO₂, and H₂O.

These bacteria also generate a lot of ATP, similar to yeast.

2. Anaerobic Respiration (without oxygen):

• Process: Some bacteria thrive in environments where oxygen is absent (e.g., deep mud or the human gut), so they rely on anaerobic respiration or fermentation.

• How it works:

Instead of oxygen, these bacteria may use other compounds, like nitrate or sulfate, to break down glucose.

Just like in yeast’s anaerobic process, the ATP yield is lower—usually 2 ATP per glucose molecule.

Depending on the type of bacteria, they might produce lactic acid (like in yogurt-making bacteria) or other byproducts like methane (in methane-producing bacteria).

Key Differences:

• Yeast typically produces alcohol and carbon dioxide during anaerobic respiration (fermentation), while some bacteria may produce lactic acid, methane, or other byproducts.

• Aerobic respiration in both yeast and bacteria is far more efficient in generating energy than anaerobic processes.