Investigating+The+Effect+of+Temperature+and+pH+on+enzyme+action

Aim of Experiment A: To find out how temperature affects enzyme action.

1. Bunsen burner, tripod stand, gauze 2. 3 water baths 3. Thermometer 4. 12 testtubes and rack 5. Measuring cylinder 6. 4 250ml beakers 7. 2 white tiles 8. 2 droppers 9. Ice cubes 10. Distilled water 11. Test tube holder 12. Stop watch 13. Goggles 14. 2% starch solution 15. 1% amylase solution 16. Hydrochloric acid solution 17. Ammonium Hydroxide solution 18. Iodine solution
 * Apparatus & Materials**

1. Label 8 test tubes, A1, A2, B1, B2, C1, C2, D1, D2. 2. Add 5 cm3 of starch solution into all tubes labelled 1. Add 3 cm3 of distilled water to D2. Add 3 cm3 of amylase to A2, B2 and C2. 3. Place A1 and A2 into a beaker of ice water, B1 and B2 into a water bath at 37c and D1 and D2 into a water bath at 37c and C1 and C2 in boiling water. 4. Leave the tubes in the water bath for 10 minutes. 5. Pour the content of A,B,C,D 2 into the test tubes A,B,C,D 1 respectively. 6. Leave the test tubes in the same enviroment as before for another 10 minutes. 7. Test the mixture in each tube with iodine solution on a white tile. 8. Record observations and make conclusions.
 * Procedure**


 * Results**

**Test Tube 1** || **Content** || **Test Tube 2** || **Content** || **Temperature** || A1 || Starch || A2 || Amylase || 0c || B1 || Starch || B2 || Amylase || 37c || C1 || Starch || C2 || Amylase || 100c || D1 || Starch || D2 || Amylase || 37c ||

**Test Tube Mixture** || **Iodine Test** || A || Dark Brown || B || Brown || C || Dark-Blue || D || Dark-Blue ||

Intepretation 1. Tubes A & B show that starch digestion has occurred as when iodine reacts with starch, it would cause the substance containing starch to turn a colour of blue-black. However, for tubes A & B, the colour remains brownish, showing that starch has been broken down by the amylase. 2. Tubes C & D. 3. Tube C was placed in boiling hot water. This resulted in the denaturation of the enzymes, where the proteins are changed. This is due to the fact that as temperature increases, the peptide bonds break slowly. Protein configuration is extremely crucial in enzymes because each shape is unique for each protein. If the enzyme is in the wrong shape, reactions will not occur. Therefore, heat caused enzyme denaturation that prevented the enzymes from reacting with the substrates (starch) and breaking them down. Since starch cannot be digested/broken down, it remains as starch in the mixture. The presence of starch causes the iodine to turn blue-black. 4. It is to act as a control experiment, where there are no starch involved in this control.

Aim of Experiment B: To find out how pH affects enzyme reaction.

Procedure 1. Label 4 tubes W, X, Y, Z, and add 2 cm3 of starch solution. Place all the tubes in water bath at 37c. 2. Add 2 cm3 of Hydrochloric acid to W, 2 cm2 of distilled water to X, 2 cm3 of Ammonium Hydroxide to Y and add 2 cm3 of amylase to W, X and Y. Also add 4 cm3 of distilled water to Z. 5) Test the solutions of all setups with iodine solution on a white tile before the experiment and after 10 minutes. 6) Record observations and make conclusions.

Results

**Test Tube** || **Iodine Test** || W || Before: Blue-black After: Blue-black || X || Before: Brown (light) After: Brown (light) || Y || Before: Brown (dark) After: Brown (light) || Z || Before: Blue-black After: Blue-black ||

Intepretation 1. Tubes X & Y show that starch digestion has occurred as when iodine reacts with starch, it would cause the substance containing starch to turn a colour of blue-black. However, for tubes X & Y, the colour remains brownish, showing that starch has been broken down by the amylase. 2. W & Z. 3. Enzymes are proteins, which are biomolecules that are made out of amino acids monomers held by hydrogen bonds and other covalent bonds. For the pH levels, it can affect the protein structure as the pH level also indicates the concentration of H ions, thus affecting the existing hydrogen bonds. 4. When the pH levels of the solution are at 7 and below, for example, all acid or neutral will allow the enzyme to not digest the starch. 5. High heat and low pH levels affect enzyme action action, denaturing proteins.