Final answer:
Glycolysis is the first stage of cellular respiration that occurs in the cytoplasm, where glucose is split into pyruvate, releasing energy to produce ATP.
Step-by-step explanation:
During glycolysis, a single molecule of glucose, which contains six carbon atoms, is split into two three-carbon pyruvate molecules. This reaction releases energy, and part of that energy is harnessed to produce adenosine triphosphate, or ATP, which is the energy currency of the cell. In the cytoplasm, glycolysis begins with the investment of ATP to help break down the glucose molecule. As the pathway continues, a net gain of two ATP is achieved. Additionally, NADH, which is a molecule that carries electrons, is produced. These electrons will be used later in the process of cellular respiration to generate more ATP. The pyruvate molecules generated from glycolysis then enter the mitochondria, where they continue through the respiration process, including the Krebs cycle and oxidative phosphorylation. However, the pathway that starts the entire respiration process and occurs in the cytoplasm is indeed the pathway of glycolysis.