Carbohydrates – monosaccharides, disaccharides, polysaccharides Flashcards
what are carbon containing molecules known as?
organic molecules
what is a monomer?
smaller units that join together to make larger molecules
give three examples of monomers
- monosaccharides
- amino acids
- nucleotides
what is a polymer?
a molecule formed when monomers join together forming long chains.
give three examples of polymers.
- polysaccharides
- proteins
- DNA/RNA
what is the basic monomer unit in carbohydrates?
Sugar (saccharide)
what is a single monomer called?
a monosaccharide
what is a pair of combined monosaccharides called?
a disaccharide
give three examples of monosaccharides
- glucose
- galactose
- fructose
give three examples of disaccharides
- maltose (glucose + glucose)
- sucrose (glucose + fructose)
- lactose (glucose + galactose)
what is the test for reducing sugars?
Benedicts test
describe the Benedict’s test
- add 2cm3 of food sample to a test tube (if it is not already in liquid form grind it up in water)
- add an equal volume of Benedict’s reagent
- heat the mixture in a water bath at 100ºc for 5 minutes
what would a positive result for the Benedict’s test for reducing sugars show?
the solution will turn from blue to a orange-brown
what colours may show in a semi-quantitive use go the Benedict’s test? (none to high concentration)
Blue – green – yellow – orange – red
describe the Benedict’s test for non-reducing sugars.
if the the Benedict’s test is carried out and produces a negative result:
* hydrolyse the non-reducing sugar
* neutralise the mixture using a sodium carbonate solution
* repeat Benedict’s test.
