Glycolysis takes place in the cytosol of the cell's cytoplasm. However, the next stage of cellular respiration known as the citric acid cycle, occurs in the matrix of cell mitochondria. Below are the 10 steps of glycolysis: STEP 1 The enzyme hexokinase phosphorylates (adds a phosphate group to) glucose in the cell's cytoplasm. In the process, a phosphate group from ATP is transferred to glucose producing glucose 6-phosphate. Glucose (C6H12O6) + hexokinase + ATP → ADP + Glucose 6-phosphate (C6H13O9P) STEP 2 The enzyme phosphoglucoisomerase converts glucose 6-phosphate into its isomer fructose 6-phosphate. Isomers have the same molecular formula, but the atoms of each molecule are arranged differently.