Cyclic Forms z Lowest energy state H C C C O C C OH HO OH HO H H H CH2OH H 1 2 3 4 5 6 β-D-glucopyranose (glucose) —an aldose a hexose an aldohexose —C1 chair conformation β-D-fructopyranose (fructose) —a ketose a hexulose a ketohexose — 1C chair conformation C C O C C H H C OH H H OH OH OH CH2OH 1 2 3 4 5 6 HCyclic Forms z Lowest energy state H C C C O C C OH HO OH HO H H H CH2OH H 1 2 3 4 5 6 β-D-glucopyranose (glucose) —an aldose a hexose an aldohexose —C1 chair conformation β-D-fructopyranose (fructose) —a ketose a hexulose a ketohexose — 1C chair conformation C C O C C H H C OH H H OH OH OH CH2OH 1 2 3 4 5 6 H