Carbohydrates Flashcards
Monosaccharides
Simple sugars containing three to seven carbon atoms
E.g glucose, galactose and fructose
Glucose
A hexose sugar that has the chemical formula C6H12O6
It is an important source of energy in humans during cellular respiration, the energy released from glucose helps to make atp
Disaccharides
When two monosaccharides join via a condensation reaction
Maltose
Glucose + glucose
Sucrose
Glucose + fructose
Lactose
Glucose + galactose
Polysaccharides
Made up of three or more monosaccharides joined together by glycosidic bonds , they may be branched or unbranded
E.g starch, glycogen, cellulose and chitin
Test for reducing sugars
Place 2ml of the substance in a boiling tube and add 10 drops of benefit is solution and place in a water bath for 3-5 minutes
A brick red precipitate suggests a large amount of reducing sugar
Test for non reducing sugar
Boil in dilute HCL and neutralise the solution by adding sodium hydrogen carbonate
Repeat the benedicts test
Functions of starch
Main energy storage material in plants and is broken down into glucose
Features of starch
Doesn’t change the water potential in a cell because its insoluble in water
Test for starch
Add a few drops of iodine solution to he sample and if starch is present then the solution will change colour from orange to blue/black
How is glycogen formed
Condensation reactions of alpha glucose
Function of glycogen
A highly branched molecule so when animals need to release energy its highly branched structure means that it can be quickly released
Glycogen in the human body
Good storage molecule because it is so compact so when blood glucose levels decrease, glycogen is broken down to release glucose -glycogenolysis
