α-D-glucose structure: alpha form of glucose

The official name for this molecule is α-D-glucose.

The "α" is the Greek letter "alpha", and tells us that the -OH (in orange) is pointing down instead of out. (If it's pointing out, then it's "beta" or "β".)

The "D-" form of glucose is the only form that can be used by plants and animals. The opposite of "D-" is "L-", which is the mirror image. It's kind of like your right hand and your left hand. Just like your left hand doesn't fit into a right glove, L-glucose doesn't fit into enzymes, the tools that your body (and animals and plants, too!) use to handle glucose.

Often the "D-" is left off of the name. If we're talking about glucose used in a living thing, then it must be "D-"!

Now if you want to sound really smart and be totally technical, you can call it α-D-glucopyranose. The "pyranose" part just means that the glucose is in a ring instead of in the open-chain form, and that the ring is made up of one O and five C's. There are other ways that the ring can be formed, but this one is the most common. By the way, "glucopyranose" sounds like (glue-koe-pie'-ran-owes). Sweet!