Can glycolysis occur in the absence of oxygen? Why or why not?

Question

This question focuses on whether oxygen is required for glycolysis to take place. It asks you to consider where glycolysis occurs in the cell, how it fits into the overall process of cellular respiration, and how energy production might differ under anaerobic (oxygen-lacking) versus aerobic conditions.

Answer 1

Hello, thank you for taking the time to post your question!

Yes, glycosis can occur in the absence of oxygen! In the process glucose is broken down into pyruvate and generates a small amount of ATP as a byproduct. None of those reactions specifically require oxygen, it just will complete the process in a less efficient way without the oxygen being present.

Hopefully that gets you moving in the right direction! Feel free to reach out with a message if you have any questions beyond that! :)

Answer 2

Yes, glycolysis can occur in the absence of oxygen. However, without oxygen, the electron transport chain cannot operate because there's no final electron acceptor. As a result, the NADH produced during glycolysis cannot pass its electrons to the chain, leading to a buildup of NADH and a shortage of NAD⁺.

Each glucose molecule metabolized through glycolysis produces 2 NADH and 2 ATP. But glycolysis requires NAD⁺ to continue. To solve this, cells switch to lactic acid fermentation under anaerobic conditions. In this process, the pyruvate molecules produced at the end of glycolysis are converted into lactate. This conversion transfers electrons from NADH back to pyruvate, regenerating NAD⁺.

By regenerating NAD⁺, lactic acid fermentation ensures that glycolysis can continue, allowing the cell to keep producing a small but vital amount of ATP even in the absence of oxygen.