carbohydrates: disaccharides and polysaccharides

maltose

glucose + glucose

sucrose

glucose + fructose

lactose

glucose + galactose

non reducing sugar

a carbohydrate that cannot donate electrons

test for non reducing sugars

negative initial benedict’s est

take sample, adding hcl and heat until boiling (breaks glycosidic bods by hydrolysing it)

use a universal indicator to check the solution is alkaline

do benedict’s test and heat

starch and glycogen properties

alpha glucose polysaccharide

insoluble and large, no diffusion, doesn’t affect water potential

osmosis is not affected

compact, stores lots in a small space, has lots of ends for enzyme action

cellulose properties

beta glucose polysaccharide

provides structure, strength and stability in a cell wall

starch structure

can be branched or unbranched

1,4 and 1,6 glycosidic bonds

coiled

glycogen structure

shorter chains

1,4 or 1,6 glycosidic bonds

cellulose structure

each glucose molecule flips 180 degrees

1. beta glucose chain, long and unbranched

2. parallel chains, cross linking hydrogen bonds

3. microfibrils, lots of parallel chains grouped together

4. forms fibres, microfibrils groups together

5. lattice structure in cell wall