For Unit 3 Biology, Signatures of Life. A brief overview of carbohydrates.
Carbohydrates are one of the 4 major groups of biomacromolecules (other groups include Proteins, Lipids and Nucleic Acids).
Carbohydrates are made up of Carbon, Hydrogen and Oxygen atoms and follow the general formula CH2On.
Monosaccharides are single sugar units, e.g: glucose and fructose
Through condensation (aka dehydration) reactions monosaccharies can be combined into disaccharides.
Disaccharides are sugar units made up of 2 sugar molecules. e.g: Sucrose( a disaccahride) is composed of one glucose molecule and one fructose molecule. Lactose (a dissacharide) is composed one glucose molecule and one galactose molecule.
Mono and disaccharides play an important role in biological systems as energy sources. They are used when energy is required quickly.
Polysaccharides are made up of many sugar molecules bound by glycosidic bonds (bonds formed through condensation reactions).
Starch – is the energy storgae unit in plants. It i smade up of many monosaccharides (glucose) combined together. Starch is insoluble, so it has little effect on osmotic balance in plant.
Glycogen – sugar storage in animals. Sugar that is not utilised by an animal is converted to glycogen and stored in the muscles and liver. When these sites are full, excess sugar is converted to fat.
Cellulose – functions as a structural carbohydrate in plants. Found in every plant cell wall. Bundles form very tough fibres.
Derivative of cellulose is Chitin. which is the main component of insect exoskeletons. Another derivative is pectin, a material that exists between cell walls to help bind them together.