Let’s discuss the three main pathways of glucose catabolism.

Select a prokaryote or eukaryote and discuss whether it uses aerobic respiration, anaerobic respiration, or fermentation.

Once you identify the catabolic pathway of your microorganism, compare it to one of the other two pathways by answering the following questions:

- Are the Krebs cycle and electron transport system used?
- What molecule is the final electron acceptor?
- How much ATP is produced?

Let's discuss the three main pathways of glucose catabolism: aerobic respiration, anaerobic respiration, and fermentation. For this discussion, I will focus on the yeast Saccharomyces cerevisiae, a eukaryote that uses both aerobic respiration and fermentation depending on oxygen availability.

Aerobic Respiration

Krebs cycle and electron transport system (ETS) are used.

Oxygen is the final electron acceptor.

Around 36-38 ATP molecules are produced per glucose molecule.

Fermentation

The Krebs cycle and ETS are not used.

An organic molecule, such as pyruvate or acetaldehyde, is the final electron acceptor.

Only 2 ATP molecules are produced per glucose molecule.

Comparatively, aerobic respiration is much more efficient at ATP production than fermentation, which highlights the role of oxygen in maximizing energy yield.