The first step in both anaerobic and aerobic respiration is called glycolysis. This is the process of taking one glucose (sugar) molecule and breaking it down into pyruvate and energy (2 ATP). We will discuss this in depth during aerobic respiration.The second step in anaerobic respiration is called fermentation. Fermentation starts with pyruvate (the end product of glycolysis).lycolysis is the first step in cellular respiration for both anaerobic and aerobic processes. Glycolysis takes place in the cytosol of a cell. In the cytosol we convert 1 molecule of glucose into 2 molecules of pyruvate.