1.3 disaccharides & polysaccharides Flashcards
1
Q
name the 3 disaccharides.
A
- maltose
- lactose
- sucrose
2
Q
what is maltose formed from?
A
alpha-glucose + alpha-glucose
3
Q
what is lactose formed from?
A
alpha-glucose + galactose
4
Q
what is sucrose formed from?
A
alpha-glucose + fructose
5
Q
how are disaccharides formed from their monomers? what bond is formed?
A
condensation reaction which forms a glycosidic bond
6
Q
what is the test with non-reducing sugars?
A
- hydrolyse the disaccharide to monosaccharides using an equal volume of acid
- put the solution in a boiling water bath for 5 minutes
- slowly add NaHCO3 (sodium hydrogen carbonate) to neutralise acid, since benedict’s solution doesn’t work at low pH
- test with litmus paper; solution must be alkaline
- carry out benedict’s test
7
Q
what is a polysaccharide?
A
polymer of monosaccharides joined by condensation reaction
8
Q
what 3 types of polysaccharides are there?
A
- starch
- cellulose
- glycogen
