The following table compiles the natural monosaccharides that contain an aldehyde group, called aldoses. The table is built starting with the smallest aldose, glyceraldehyde (aldotriose). Erythrose and threose (aldotetroses) are obtained from glyceraldehyde by adding a fourth carbon. The addition of a fifth carbon to the aldotetroses gives rise to the aldopentoses, and these in turn form the aldohexoses by adding a sixth carbon.

Sugars that differ at only one chiral center are called epimers. Thus, galactose is epimer of glucose since it differs in the chiral center of carbon 4. Mannose is also epimer of glucose, both sugars differ in the chiral center of position 2.

D-Glucose

D-Mannose

D-Glucose

D-Galactose