Recall that glycolysis is the metabolic pathway that breaks down glucose into pyruvate, producing ATP and NADH in the process.
Understand that glycolysis does not require oxygen and occurs in the part of the cell where enzymes and substrates are freely available without membrane barriers.
Identify the cytosol (also called cytoplasm) as the fluid portion of the cell outside organelles where many metabolic reactions take place.
Recognize that the nucleus contains DNA and is not involved in glycolysis, and that mitochondria are involved in later stages of cellular respiration, not glycolysis itself.
Conclude that glycolysis occurs in the cytosol (cytoplasm) because it is the site where glucose is enzymatically broken down before entering mitochondria for further processing.