Carbohydrates WJEC GCE BIOLOGY Carbohydrates 2 6 Carbohydrates
Carbohydrates WJEC GCE BIOLOGY Carbohydrates 2. 6
Carbohydrates are made from CARBON, HYDROGEN and OXYGEN They STORE ENERGY in plants and animals Plant cell walls depend on the structural role of some carbohydrates Carbohydrates WJEC GCE BIOLOGY CARBOHYDRATES MONOSACCHARIDES DISACCHARIDES POLYSACCHARIDES
Monosaccharides are small organic molecules used as bulding blocks for more complex carbohydrates. Click each of the blue boxes to work through the slide. General Formula (CH 2 O)n So, when n=3 Carbohydrates WJEC GCE BIOLOGY When n=5 What does the ‘n’ stand for? Number of Carbon atoms TRIOSE, e. g. glyceraldehyde In metabolic reactions When n=6 PENTOSE, e. g. ribose – HEXOSE, e. g. glucose - formation of nucleic acid main source of energy next
Isomerism in Glucose C 6 H 12 O 6 Alpha-glucose CH 2 OH Oxygen Hydrogen Carbon Hydroxide (OH) beta-glucose Carbohydrates WJEC GCE BIOLOGY CH 2 OH Show structural change
Disaccharides form when two monosaccharide units join forming a glycosidic bond, by a condensation reaction. A disaccharide can be made from two of the same monosaccharide molecule or from two different ones. The combination of monosaccharides determines which disaccharide is formed. MONOSACCHARIDES DISACCHARIDE Carbohydrates WJEC GCE BIOLOGY GLUCOSE WATER SUCROSE MALTOSE GALACTOSE FRUCTOSE GLUCOSE LACTOSE
Forming Disaccharides Glucose CH 2 OH H C C H OH OH O H H H C O H C C OH H C OH OH C C H OH Maltose Carbohydrates CH 2 OH H C C H OH OH O H H H C C C OH OOH H H O WJEC GCE BIOLOGY CH 2 OH Glycosidic Bond O H OH H C C C H OH This is a CONDENSATION reaction, where a water molecule is lost.
Polysaccharides are large complex molecules known as POLYMERS. What is polymerisation ? Click the bubble for the answer Polysaccharides Carbohydrates WJEC GCE BIOLOGY Polymerisation is the process of bonding many MONOMERS by condensation reactions to form one large molecule. Monomer STARCH CELLULOSE GLYCOGEN Return to isomerism of glucose α Glucose β Glucose α Glucose What is a monomer? Monomers are the individual monosaccharides which join to form the polysaccharide. Glycosidic bond 1 -4 1 -6 Next
Forming polysaccharides Glucose CH 2 OH O C OH H C C H OH H H C C C OH H C C H OH OH H O O C OH H O H CH 2 OH H H C C C OH H C C H OH OH H O O H CH 2 OH OH H O H H H C C C OH H O OH O CH 2 OH H C C C H OH H Carbohydrates WJEC GCE BIOLOGY In this example, 3 condensation reactions have produced 3 water molecules to produce the polysaccharide. A HYDROLYSIS reaction (addition of water) reverses the reaction and splits the polysaccharide releasing 3 monosaccharide molecules. OH
Carbohydrates WJEC GCE BIOLOGY You can give this question a go, in order to prove your understanding:
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