So if we have an aldehyde group on that sugar molecule, well, then it reacts with an alcohol group on that same sugar molecule to form a hemicata. And likewise, if we have a ketone instead of the aldehyde, that ketone will act as the electrophile reacting with the nucleophile, one of the hydroxyl groups on that sugar molecule, to form a hemiketel. So let's begin by focusing on aldohexos. And the aldohexos that we're going to use as our prototypical example is glucose, more specifically, the D glucose. So remember, the de glucose simply means this blue hydroxyl group found on the last stereogenic carbon. Carbon number five points to the right side and not to the left side.