ENZYME EXPERIMENTS 1. Effect of Temperature on Enzyme Reaction Speed. Ways of working: Provide 8 (eight) test tubes. Fill 4 (four) tubes with 2.5 mL milk; and 4 (four) other tubes with 1 mL of 0.5% rennin Pair a tube containing 2.5 mL of milk with a tube containing 1 mL rennin 0.5% (example: tube number 1 with 5, tube number 2 with 6, etc.). Insert one of the pair of tubes (first) into the glass chemistry containing ice, leave the second pair of tubes at room temperature, the third pair of tubes in a water bath at 37-400 C, and the fourth pair of tubes in a water bath at 75-800 C. After 2 minutes, record the actual temperature of each pair of tubes. Pour the rennin solution into the partner's milk tube, stir immediately well. Observe every ÿ 1 minute for a period of 5 minutes. Note whether the milk has curdled and note the time the clotting. The tube contains milk that has not curdled after 5 minutes, wait for 30 minutes, while observing every 5 minutes. 2. Effect of Enzyme Concentration on Reaction Speed. Ways of working: Provide 4 (four) test tubes. Fill the first tube with 8 mL of milk, and place it in a water bath at 370 C. Fill the 2nd, 3rd, and 4th tubes. each with 1 mL, 0.5 mL, and 0.25 mL of 0.25% rennin. Add 0.5 mL of water in the 3rd tube and 0.75 mL of water in the 4th tube, so The enzyme concentration in the three tubes is proportional to 1: 0.5: 0.25. Put the three tubes (2nd, 3rd, and 4th tubes) in a water bath at 370 C. After 2 minutes, add 3 mL of milk from the 1st tube to the in these tubes. Mix and leave. Determine the time necessary to coagulate the milk in each tube. Explain the results obtained. 3. Effect of Substrate Concentration on Enzyme Reaction Speed. Ways of working: Provide 3 (three) test tubes. Fill the first tube with 3 mL of milk, the second tube with 2 mL of milk + 1 mL of water, and the third tube with 1.5 mL of milk + 1.5 mL of water. Place all tubes in a water bath at 370 C. Add 1 mL of 0.2% rennin to each tube. Mix well. Note the time required for the milk to coagulate in each tube. 4. Effect of Antiseptic Substances on Enzyme Reaction Speed. Ways of working: Provide 5 (five) test tubes and fill them with: Put all the tubes into a water bath at 370 C. Add 1 mL rennin 0.2% into each tube. Mix well and observe. Note Does clotting occur in the first 4 tubes? If so, compare the speed with the 5th tube (control). Explain the purpose of this experiment.