The aldoses are one of the two families of Ose S with the Cétose S. the function Carbonyle is a function Aldéhyde, and it defines the position of the first Carbone. Principal aldoses are D Glycéraldéhyde (Triose), D Ribose (pentose), and the Hexose S: D Glucose, D Mannose and D Galactose. If the carbonyl group is located at one of the ends of the carbonaceous chain, the ose is an aldehyde, one speaks about aldose. If on the contrary the carbonyl group is located on another position, the ose is a ketone, one speaks then about ketosis.