1.3 Carbohydrates- Disaccharides and polysaccharides Flashcards
Name 3 disaccharides
Maltose
Lactose
Sucrose
all have the formula c12h22 o11 due to Water molecule being rermoved
What is the equation for how each of the three disaccharides are formed
Glucose + Glucose—>Maltose + water
Glucose + Fructose—-> Sucrose + water
Glucose + Galactose—-> Lactose + water
How do disaccharides form (3)
- Formed via a condensation reaction which releases a water molecule
- Joined together by a glycosidic bond
- Made up of two monosaccharides
Describe the test for non reducing sugars
- Do benedicts test and stays blue/negative
- heat in a boiling water bath with acid (to hydroloyse into reducing sugars)
- Neutrlise with alkali
- heat in a boiling water bath with benedicts solution
- positive result is either green/yellow/orange/red precipitate
What are polysaccharides
Many monosaccharides joined together with glycosydic bonds
How are polysaccharides formed
Formed by many condensation reactions releasing water molecules
What happens when water is added to a disaccharide (hydrolysis)
It breaks the glycosidic bond releasing the constituent monosaccharide
What is a universal advantage that all polysaccharides have
They are large and insoluble so they are suitable for storage
Cannot diffuse out the cell
Have no osmotic effect
Describe the test for starch
Add iodine solution
Positive result: colour changes from orange to blue black
Describe the test for reducing sugars
Add benedicts solution to a sample
Heat in a water bath
Positive reuslt is blue- green-red
