Carbohydrates in living organisms:
Carbohydrates make up about 10% of the organic matter of a cell. The functions of carbohydrates in organisms include:
· energy source- released from glucose during respiration
· energy store- e.g. starch
· structure- e.g. cellulose
Some carbs also form part of larger molecules (e.g. nucleic acids, glycolipids).
Carbs contain the elements C, H and O. The term carbohydrate essentially means hydrated carbon, because the elements are found in the proportions Cn(H2O)n.
The simplest carbohydrates are called monosaccharides. These are the monomers (basic units) of carbohydrates. All larger carbs are made by joining monosaccharide’s together.
There are a number of diff. monosaccharide’s; containing between 3-6 carbon atoms. All have very similar properties:
· soluble in water
· sweet tasting
· form crystals
The monosaccharides are grouped according to the no. of carbon atoms in the molecule:
· 3-carbon monosaccharide = triose sugars
· 5-carbon atoms monosaccharide = pentose sugars
· 6-carbon monosaccharide = hexose sugars.