The simple carbohydrate that provides structure to cell walls and cells is

Sugar that encompasses the monomer monosaccharides, small polymers called oligosaccharides, and large polymers called polysaccharides. They are molecules formed from a carbonyl (C=O) group, several hyrdroxyl (-OH) groups, and several carbon-hydrogen bonds. They serve as raw materials for synthesizing other molecules, provide fibrous structural material, indicate cell identity, and store chemical energy. 
Hope this help