CHAP 3

• carbhydrates exists as single sugars,double sugars nd complex sugars,
• single sugars are glucose[animal n plants] and fructose[plants]. they are called monosaccharides. single sugars is a basic unit of carbohydrates passed through cell membranes and absorbed In the cells.
• double sugars are formed when 2 single sugars bond. [maltose and sucrose.] they are called disaccharides and can be split using enzymes. they have the same chemical formula but different arrangements of atoms.
• complex carbohydrates are starch,cellulose and glycogen.
• in plants, excess glucose = starch but in humans, excess gucose=glycogen
• benedicts solution is for testing for reducing sugars. red=most green=traces of reducing sugar. [add food, benedicts solution,shake tube , put in boiling water
• complex carbohydrates is made up of many similar molecules of simple sugar joined to become a large molecule.
• starch = glucose molecules. > storage form of carbohydrates in plants.
• cellulose=glucose molecules > cell Wall > acts as a fibre in plants.
• glycogen = branched glucose molecule.>storage form of carbohydrates in animals.
• functions of carbohydrates are energy storage, structural support, and making nectar in flowers.
• iodine test is for presence of starch. yellowish brown to blue black if starch present.
• fats are a type of lipid that can be broken down into fatty acids and gycerol
• function of fats are storage of energy,insulating material and reduce water loss.[skin]
• ethanol test is for fats. if it turns cloudy, it is fat. [ethanol and water added]
• proteins are always present in cells.[amino acids molecules join in a linear manner to form a polypeptide.]
• proteins synthesise protoplasm for growth and repair of cells, synthesise hormones and enzymes , form antibodies combat diseases]
• biuret test is for proteins. blue solution turns purple = proteins present. [add food sample > add equal volume of biuret solution > shake well > wait 5 mins.
• for solid fats/proteins, we can use a mortar and a pestle before conducting tests