What process do cells use to release energy in the absence of oxygen?

Fermentation is the process that cells use to release energy when oxygen is not available. This anaerobic process allows cells to generate ATP, which is the energy currency needed for various cellular activities. During fermentation, glucose undergoes breakdown in a way that does not require oxygen, producing byproducts such as lactic acid in animals or ethanol and carbon dioxide in yeast. This enables organisms to sustain energy production in low-oxygen environments, crucial for survival and function in many life forms.

In contrast, glycolysis involves the initial breakdown of glucose into pyruvate, which can occur with or without oxygen, but does not produce energy independently in the absence of oxygen. Translation is a process related to protein synthesis, and mitosis refers to cell division, both of which do not directly relate to energy release in the absence of oxygen. Thus, fermentation stands out as the correct answer in the context of energy production under anaerobic conditions.