1. Proteins s are compounds of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur, phosphorus s amino acids: –unit of proteins –about 20 different types –essential and non-essential types

2. An amino acid molecules H 2 N amino group COOH carboxyl group C R H

3. The condensation and hydrolysis of a polypeptide 5 1 4 3 2 1 2 3 4 5 hydrolysiscondensation

4. Condensation of two amino acid to form a dipeptide H2NH2NC R1R1 H C O OH H N H C H R2 COOH H2N C R1R1 H O H C H R2R2 COOH C---N H2O

5. Functions of proteins s components of cell membranes and cytoplasm s for growth and repair of body cells s for making enzymes, hormones, antibodies and haemoglobin s provide energy during starvation s excess protein is under deamination in the liver s deficiency disease: Kwashiorkor

6. Test for proteins / Biuret test egg white solution 1 cm 3 NaOH solution Put CuSO 2 solution drop by drop, and shake the mixture after addition of each drop Positive result: purple colour