as-u1-2.3 carbohydrates-disaccharides and polysaccharides
TRANSCRIPT
What’s the question? 1.Polymer
2.Monosaccharide
3.Red
Here's the answers, all you
have to do is write the
questions!
?
?
?? ??
Carbohydrates-Polysaccharides
Objective: To understand how monosaccharides form polysaccharides.
Outcomes: ~ Describe what a disaccharide is and name examples. ~ Explain how monosaccharides are linked to form polysaccharides.~ Explain how to carry out a test for non-reducing sugars and for starch.
Keywords
DisaccharidePolysaccharideCondensation reactionGlycosidic bondHydrolysis
Thursday 13 April 2023
DisaccharidesMonosaccharide + monosaccharide = disaccharide
Monosaccharide
Monosaccharide
Disaccharide
Glucose Glucose MaltoseGlucose Fructose SucroseGlucose Galactose Lactose
How?
glucose + glucosemaltose + water
Condensation reaction
Glycosidic bond
Test for non-reducing sugars (Sucrose)1.Confirm that the sample you’re
testing is not a reducing sugar.
2.Add 2cm3 of food sample (liquid form) to 2cm3 of dilute hydrochloric acid and place in a gently boiling water bath for 5mins.
3.Slowly add sodium hydrogen carbonate solution. Check the solution is then neutral.
4.Re-test this solution now again with Benedict’s.
Test for non-reducing sugars (Sucrose)Hydrochloric acid is added to the sample because…
Sodium hydrogencarbonate is added because…
If a non-reducing sugar is present, the Benedict’s reagent will now turn red because…
PolysaccharidesPolymers.
Large molecules yet compact.
Insoluble.
e.g. Starch
Hydrolysed into glucose.
Starch granules in plant cells
e.g. Cellulose
Provides structural support in plant cells.
Test for starch1.Add two drops
of sample onto a spotting tile.
2.Add two drops of potassium iodide.
3.Starch indicated by blue-black result.
2.3 Carbohydrates-disaccharides and polysaccharidesForming and breaking glycosidic bonds
Complete the diagrams below to show how glycosidic bonds can be formed and broken.
This type of reaction is called a…The molecule formed is…
This type of reaction is called a… The molecules formed are…