Monosaccharides are the simplest carbohydrates since they cannot be hydrolyzed into smaller carbohydrates. Chemically they are aldehydes or ketones possessing two or more hydroxyl groups, and are important as building blocks (such as D-ribose and 2-deoxy-D-ribose) for the synthesis of nucleic acids, as well as fuel molecules in glycolysis.https://www.creative-biolabs.com/glycoprotein/custom-monosaccharide-synthesis.htm