1. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Define the structure of carbohydrates, fats and proteins. Carry out tests to identify starch, reducing sugars, fats and proteins. State the role of water in living organisms Learning Outcomes

2. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 2 hydrogen atoms attached to the oxygen atoms V-shaped molecule Stronger pull of O atom result in H 2 O becoming slightly polar O atom is more negative, H atoms are more positive Water 3.1 The Building Materials of Life

3. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Water has a high heat capacity due to the many bonds between water molecules. Water has a high heat capacity 3.1 The Building Materials of Life

4. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 As water loses heat, the molecules slow down. More bonds are formed between the molecules. Ice is formed and it is less dense than water since its molecules are further apart than in liquid state. Ice is Less Dense than Water 3.1 The Building Materials of Life

5. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Cohesive force – ease with which hydrogen bonds are formed between water molecules. Adhesive force – attraction between two different kinds of molecules. Cohesive and Adhesive Forces 3.1 The Building Materials of Life

6. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Also a very good solvent – due to it being slightly polar. Water as a Solvent 3.1 The Building Materials of Life

7. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Absorbs and removes heat produced by metabolic activities. Removes heat by evaporation of sweat. Its unique density as ice results in ice floating over slightly warmer water. –Insulates water from further loss of heat. –Ensures survival of aquatic organisms. Forms a large part of the cytoplasm of the cell, tissue fluid and transporting medium. In plants, it helps the cells to maintain turgor pressure and keep their shape. Also essential in photosynthesis. Role of Water in Living Organisms 3.1 The Building Materials of Life

8. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 3.1 The Building Materials of Life Contain carbon, hydrogen and oxygen. Hydrogen : Oxygen  2 : 1 Chemical formula: C m (H 2 O) n Carbohydrates

9. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Monosacharides (single sugars) are carbohydrates which cannot be broken down into simpler form. E.g. glucose, fructose, galactose. Sweet and soluble Carbohydrates 3.1 The Building Materials of Life

10. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Disaccharides (double sugars) are created when two mono-saccharides become linked. Sweet and soluble Carbohydrates 3.1 The Building Materials of Life

11. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Sugars may be classified as reducing or non- reducing sugars Eg. glucose, fructose, maltose, lactose are reducing sugars Carbohydrates 3.1 The Building Materials of Life

12. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Test for Reducing sugars Add 2ml of Benedict’s Solution to 2ml of test solution in a test-tube. Shake well to mix. Place test-tube in boiling water bath for 5 min. Solution turns green = Solution forms yellow ppt = Solution forms ornage-red ppt = Solution remains blue =

13. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Polysaccharides are long chains or polymers of monosaccharides. The chains produced can be branched or unbranched. The chains may also be folded, thus making them compact and ideal for storage. The large size of the molecules makes them insoluble so do not affect water potential and they cannot easily diffuse out of the cell. Functions: mainly for storage and provide structural support. Carbohydrates 3.1 The Building Materials of Life

14. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Storage polysaccharides: – Starch is a polymer of glucose molecules. – Stored as starch granules in plastids in plant cells or tissue. Carbohydrates 3.1 The Building Materials of Life

15. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Storage polysaccharides: – Glycogen is also a polymer of glucose. – Primary store of carbohydrates in animals. – Stored in liver and skeletal muscles of vertebrate animals. Carbohydrates 3.1 The Building Materials of Life

16. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Carbohydrates Structural polysaccharides: – Cellulose is the most abundant organic compound on the Earth. – Long cable-like bundles of fibrils in the cell walls of all plant cells. 3.1 The Building Materials of Life

17. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Carbohydrates Structural polysaccharides: – Most animals do not have the enzymes to break the molecular linkages. – However, it aids peristalsis. – For herbivores, cellulose is digested by micro-organisms present in the gut of those animals. 3.1 The Building Materials of Life

18. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Why Glycogen and Starch are suitable storage materials? Insoluble so Large molecules so Easily broken down (hydrolysed) so Molecules have compact shapes, folded so

19. Biological Molecules T H E M E O N E : P R I N C I P L E S O F B I O L O G Y C h a p t e r 3 Test for starch Add 2ml of Iodine solution to 2ml of test solution. Shake well to mix. Solution turns blue-black = If solid, its stained blue-black = Solution remains yellowish brown =