And next we transform the open chain into its closed cyclic chain. And so this is the final product in step number two. This is what we call fructose six phosphate. So in the second step, the enzyme phosphoglucose isomerase transforms the glucose which is an aldos, it contains an aldehyde group into a fructose, which is a keto that contains this ketone group. So this is a ketone and this is an aldehyde. So we see that in step two of stage one, the entire point is to transform an aldos into a keto.