Carbohydrates Monosaccharides – e.g. glucose, fructose, galactose General formula (CH2O)n (n=3-7) 3C = triose 5C = pentose 6C = hexose Disaccharides – e.g. sucrose – glucose+fructose lactose – glucose+galactose maltose – glucose+glucose Polysaccharides – e.g. starch, glycogen, cellulose – 000’s glucose molecules.

The Different Isomers of Glucose OH H HO CH2OH  

NUMBERS! 6 O OH H HO CH2OH 5 4 1 3 2

Condensation Reaction & the Glycosidic Bond OH H HO CH2OH O OH H HO CH2OH H2O

MALTOSE (a dissacharide) OH H CH2OH HO 1,4 glycosidic bond Monosaccharides are joined by a condensation reaction. (Water is eliminated). A glycosidic bond is formed producing a disaccharide.

Hydrolysis of carbohydrates CH2OH HO H2O

A glycosidic bond is broken. OH H HO CH2OH O OH H HO CH2OH Polysaccharides and disaccharides are split by a hydrolysis reaction. (Water is required). A glycosidic bond is broken.

Plants Animals Starch Cellulose Glycogen Storage Structure Storage Carbohydrates Storage Structure Starch Cellulose Glycogen Plants Animals Storage Gklue tick box into notes. Students complete it as you go along. And add any extra notes

 Starch - Amylose 6 5 4 1 3 2 These are 1,4 glycosidic bonds O OH H HO CH2OH  5 4 1 3 2 O OH H HO CH2OH O OH H HO CH2OH O OH H HO CH2OH O OH H HO CH2OH These are 1,4 glycosidic bonds

Starch - Amylose Spiral shape makes it compact and largely insoluble. Does not affect osmosis or diffuse out of cells. This makes it a good storage molecule. Is hydrolysed slowly to α-glucose for use in respiration by amylase.

 Glycogen 6 5 1 4 3 2 1,6 glycosidic bond 1,4 glycosidic bonds O OH H HO CH2OH  O OH H HO CH2OH O OH H HO CH2OH 1,6 glycosidic bond O OH H HO CH2OH 1,4 glycosidic bonds

Glycogen Large and mostly insoluble. Does not affect osmosis or diffuse out of cells. Has many terminal glucose molecules. Is hydrolysed quickly to α-glucose for respiration by glycogen phosphorylase. Lucose

Cellulose  These are still 1,4 glycosidic bonds CH2OH O OH H HO CH2OH

Cellulose

Cellulose Formation of hydrogen bonds now possible

Cellulose Adjacent chains held together with hydrogen bonds to form microfibrils Prevents hydrogen bonding with water so cellulose is highly insoluble Strong microfibrils able to form a dense network to build cell walls.

Starch α Unbranched chains of a-glucose held together with 1,4, glycosidic links. Angle of OH groups involved in glycosidic links produces a spiral molecule. Able to form limited hydrogen bonds with water so is only slightly soluble in water. Broken down (slowly) to a-glucose with digestive enzymes for slow release of glucose for respiration   Molecule is compact and insoluble so does not affect osmosis Will not diffuse out of cells Glycogen Branched chains of a-glucose held together with 1,4, glycosidic links and 1,6 glycosidic links. Branches produce many terminal glucose molecules. Broken down readily to a-glucose with digestive enzymes for quick release of glucose for respiration Cellulose β Long chains of B-glucose held together with 1,4 glycosidic links. Adjacent chains are held together by crosslinks of hydrogen bonds to form microfibrils. OH groups are unavailable to form hydrogen bonds with water molecules so cellulose is highly insoluble. Difficult to hydrolyse with digestive enzymes Strong and insoluble Forms a dense matrix Used to build cell walls