Introduction to Sugar Structures

Sugars are polyhydroxy aldehydes or ketones. A sugar with 5 carbon atoms is a pentose. The following diagrams are equivalent except that the one on the right conveys the directions in which the groups point. Is it a pentose ?

YES

NO

A sugar with 6 carbon atoms is a hexose. Few natural sugars have other than 5 or 6 carbon atoms.
Let's see some sugars to see which are pentoses and which are hexoses. Select with the chooser.

 Continue on to stereoisomerism