Carbohydrates Flashcards
(10 cards)
What are the types of carbohydrates? + examples for each
Monosaccharides
- Glucose
- Fructose
- Galactose
Disaccharides
- Maltose
- Sucrose
- Lactose
Polysaccharides
- Starch
- Glycogen
- Cellulose
Define a monosaccharide.
The monomers from which larger carbohydrates are made.
How are disaccharides formed? + equations
From the condensation of 2 monosaccharides
- Glucose + Glucose = Maltose
- Glucose + fructose = Sucrose
- Glucose + Galactose = Lactose
What is an isomer?
When molecules have the same molecular formula bot the atoms are arranged differently.
Glucose has 2 isomers, what are they?
Alpha glucose and Beta glucose
How are polysaccharides formed?
They are formed by the condensation of many glucose units, including starch, glycogen, cellulose
How is the structure of glycogen related to its function?
Its function is to be an energy store in animal cells.
Structure
- polysaccharide of alpha glucose
- branched glycosidic bonds
Structure related to function
- branched - can be rapidly hydrolyzed to release glucose for respiration to provide energy
- Large polysaccharide molecule - cant leave cell
- insoluble in water - water potential of cell is not affected, and so no osmotic effect
What is the test of reducing sugars?
1) Add Benedict’s reagent to food sample
2) Heat in a boiling water bath
3) If positive, it appears orange/red at high amounts. if not, it is blue.
What is the test for non reducing sugars?
1) Add equal volume of a sample and dilute hydrochloric acid to hydrolyse the sugar
2) Heat in a water bath
3) Neutralise with sodium bicarbonate
4) Carry out normal benedict test
5) If a non reducing sugar is present, an orange/red precipitate is formed
What is the test for starch?
1) Add iodine dissolved in potassium iodide to solution and stir it
2) A blue/black colour = starch is present
