Carbohydrates contain carbon, oxygen and hydrogen.
Carbohydrate monomers are called monosaccharides
e.g. glucose and
fructose.
Two monomers are joined by a glycosidic
bond to form a disaccharide e.g. sucrose.
Carbohydrate polymers e.g. starch, glycogen and
cellulose are formed from many monomers joined by
glycosidic bonds.
The bonds between the monomers in disaccharides and
polysaccharides can be broken by hydrolysis
.
Carbohydrates are important sources and stores of
chemical energy. There are chemical tests to indicate if they are in food.
A condensation reaction forms a bond between a carbon atom from each sugar.A glycosidic bond is broken by the addition of water. Hydrolysis can be carried out by warming with an acid or by an enzyme.Reducing sugars (e.g. glucose) give a yellow or red colour change when heated with Benedicts reagent. Non-reducing sugars do not produce the colour change unless they are first hydrolysed with acid.
