A tetrose is a monosaccharide with 4 carbon atoms.
They either have an aldehyde functional group in position 1 (aldotetroses) or a ketone functional group in position 2 (ketotetroses).
The aldotetroses have two chiral centres ("asymmetric carbon atoms") and so 4 different stereoisomers are possible.
The naturally occurring aldotetroses are:
The only naturally occurring ketotetrose is D-Erythrulose.
See also