1. What are enzymes made of? Enzymes are protein molecules, and so are made up of amino acids. These amino acids are joined together in a long chain, which is folded to produce a unique 3D structure.

2. Why are enzymes so specific in their reactions?

3. Characteristics of enzymes Enzymes speed up chemical reactions Enzymes are required in minute amounts Enzymes are specific  Lock and key hypothesis

4. Enzymes speed up chemical reactions Enzymes speed up a chemical reaction by lowering the activation energy needed to start the reaction.

5. Enzymes are required in minute amounts Enzymes are very efficient molecules. Remain unchanged in the reactions they catalyse, the same enzyme molecules can be used over and over again.

6. Enzymes are specific Each chemical reaction inside a cell is catalysed by a unique enzyme Specific due to 3D shape Lock and key hypothesis + +

7. Enzyme specificity means that each chemical reaction inside a cell is catalysed by a unique enzyme.

8. Why are enzymes so specific? Enzymes are very specific about which reactions they catalyze. Only molecules with exactly the right shape will bind to the enzyme and react. These are the reactant, or substrate, molecules. The part of the enzyme to which the reactant binds is called the active site. Active sites

9. What happens at the active site? In the same way that a key fits into a lock, so a substrate is thought to fit into an enzyme’s active site. The enzyme is the lock, and the reactant is the key. enzyme substrate + enzyme-substrate complex ↔ products enzyme + ↔ + ↔↔ +

10. Lock and key hypothesis The substances on which enzymes act are called substrates. Active sites are depressions or ‘pockets’ on the surface of an enzyme molecule into which the substrate molecule(s) can fit- just like a lock and key.

12. Effects of temperature on enzyme activity

13. Optimum temperature for typical human enzyme Optimum temperature for thermophilic bacteria

14. Effects of pH on enzyme activity Optimum pH for pepsin Optimum pH for trypsin

15. Yesterday, Sharon wanted to make pineapply jelly for her mother’s birthday. So, she used fresh pineapple for the 1 st tray and canned pineapple for the 2 nd tray. However, her jelly using the fresh pineapple did not set and was too runny! What went wrong with her preparation?

16. Fresh pineapples could not set jelly because of the acids that digest gelatin. Probably, she did not put it in the fridge after boiling the gelatin. The presence of fruits does not affect jelly at all. Canned pineapple did not digest gelatin because very few active enzymes were present. Vivek KimEve

17. What I have learned today? M i n d s p l a t t e r 32 25 43 14