Now, the reaction as shown on the board is actually the sum of two individual reactions. So this is actually the overall net reaction of the sum of two different reactions that are not shown on the board. But I'd like to talk about them for just a moment because they actually demonstrate the importance of biotin. So what happens in step number one in this reaction? So in step number one, we have the hydrolysis of ATP by this carboxylase and the energy that is released in the hydrolysis of ATP helps us attach a carbon dioxide onto the biotin. So in step number one we form, and that's not shown aboard, but we form a complex that consists of carbon dioxide attached onto biotin, which is also attached onto the carboxylase.