And so we see a low PH can actually inhibit the activity of the phosphorptokinase. This is because as the cells rush to meet the high ATP demands fermentation produces lactic acid which dissociates into H plus ions and lactate ions and that increases acidity, drives the PH down and that can cause damage to that tissue. And so to prevent this from happening the glycolytic cycle is essentially turned off by inhibiting the phosphor fructokinase. Now let's move on to hexokinase and let's recall the first three processes in glycolysis. So in step one we have glucose transformed into glucosex phosphate by hexokinase. This is also an irreversible process.