Now we're going to move on and discuss the third class of biomolecules we call carbohydrates, or simply sugars. Now, in nature, the organism use sugars for a variety of different ways. And in this lecture, we're going to briefly discuss four different different roles that sugars actually play. Now, there are many different types of sugar molecules, but the major sugar molecule that we use inside our body is glucose. Now, where does glucose, and then generally, where do sugar molecules actually come from? Well, sugar molecules are produced by plants.