Why Is Galactose Classified as a Simple Sugar?

By Robin Higgins

Galactose can have a variety of different cyclic structures depending on the situation. Find out why galactose is classified as a simple sugar with help from an experienced biology and chemistry professional in this free video clip.


Hi, I'm Robin Higgins, and this is "why is galactose classified as a simple sugar?" Alright, so, here we have one of the forms of the galactose, and so it can actually form a variety of different cyclic structures, or it can be acyclic. But, in this example, we have alpha-D-galacto-pyramose, and so, we can see that in general, it looks like one ring, and then a bunch of OH groups hanging off that ring. Now, if we look here at sucrose, we see two rings connected by an oxygen and so, the name for this is a monosaccharide, and the name for this would be because two, a disaccharide. So, a simple sugar is a monosaccharide. So, one way of saying a simple sugar is just monosaccharide, but what that means is that you can't break it up in any way and then get more sugars. So, if you broke this bond, all of a sudden, you'd have two different sugars, but you can't break anything here that will give you more sugars. So, you can't hydrolyze it and end up getting more sugars, so that's why it's called simple, simple sugar, it's just one, because there aren't just mono and di. You can get sugars that are, you know, really, as many as you can imagine all tied together. So, we wanna classify the ones that are just one by themselves, the simplest building blocks as their own special names, so that's why it gets called this. I'm Robin Higgins and this is "why is galactose classified as a simple sugar?"