Carbohydrates AS Flashcards
define monomers
individual molecule from which polymers are made
define polymer
chains of repeating monomer units
name a monosaccharide
glucose, galactose, fructose
what does glucose and glucose make?
maltose
what does glucose and fructose make?
sucrose
what does glucose and galactose make?
lactose
define disaccharide
2 monosaccharides joined
define polysaccharide
many monosaccharides joined in condensation reactions
define and name reducing sugars
can donate electrons. all monosaccharides and maltose
which sugars are non-reducing
sucrose, lactose and polysaccharides e.g. starch
how are monosaccharides joined together
with a condensation reaction to form a glycosidic bond
how do you break down disaccharides
add water on a hydrolysis reaction, breaking glycosidic bonds
test for a reducing sugar
add benedicts reagent and heat. turns red/yellow/green
test for a non-reducing sugar
add benedicts and heat. stays blue. then add hydrochloric acid to hydrolyse add sodium hydrogen carbonate solution to neutralise then add benedicts solution and heat turns red/yellow/green
test for starch
add iodine solution. Turns blue/black
adaptations of starch
coiled to make it compact. insoluble doesn’t affect water potential. long chain cant cross cell membrane. polymer of alpha glucose so provides glucose for respiration. branched so glucose is easily ready.
how does cellulose give cells strength
long unbranched beta glucose. several chains lie side by side and form microfibrils. H bonds hold chains together. strong in large numbers. only 1,4 glycosidic bonds.
adaptations of glycogen
shorter, more branched than starch can be hydrolysed easier. spiral shape compact. 1,4 and 1,6 glycosidic bonds.
how to find quantity of reducing sugar using only benedicts test
filter and dry, find mass/weight
method for using a calibration curve to find sugar concentration
make known sugar concentration. use colorimeter to measure absorbance of each and plot curve on graph. find conc. of sample from calibration curve.
