Sugars
The more common form of glucose has a ring structure. This is alpha-D-glucose:
This is beta-D-glucose:
Sucrose
Sucrose is a disaccharide derived from glucose and fructose (it is essentially glucose and fructose connected by an acetal linkage). It is one of the only natural chemicals that are consumed by humans in unmodified form (like water and NaCl). It is broken down by enzymes in the body to give glucose, which is then diffused into the cells to give the body energy.