1. 11 PROTEINS

2. 2 Learning Outcomes/Objectives:  State the elements in proteins.  State the various structure of proteins.  Explain the formation and breakdown of dipeptides and polypeptides.  Explain the meanings of essential amino acids and non essential amino acids.

3. 3 Introduction  Protein are large complex organic molecules which play diverse roles in living organisms.  Proteins made up of such elements as carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus.

4. 4 Amino acid + amino acid dipeptide + water Polypeptides + water dipeptides or amino acids condensation hydrolysis

5. 5 Examples  Protein sources: egg, meat, milk, yoghurt and etc.

6. 6 Protein Structures a)Primary structure b)Secondary structure - alpha-helix - beta-pleated sheets c)Tertiary structure d)Quaternary structure

7. 7 a)Primary structure  The linear sequence of amino acids in a polypeptide chain.

8. 8 b)Secondary structure i) Alpha-helix -Three dimensional arrangement of amino acids with the polypeptide chain in a cork screw shape. ii) Beta-pleated sheet -Polypeptide chains are arranged side by side.

9. 9 c)Tertiary structure  The overall three dimensional shape of a polypeptide chain.

10. 10 d)Quaternary structure  The combination of two or more tertiary polypeptides that makes up a protein.

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12. 12 Amino Acids  There have two types of amino acids: i) essential amino acids ii) non essential amino acids  Essential amino acids are amino acids that cannot be synthesized by the body. Example: Leucine  Non essential amino acids are amino acids that can be synthesized by the body. There are 11-non essential amino acids. Example: Alanine

13. 13 Thank You