Activity of an Enzyme

1) Knowing that enzymes act as catalysts in the chemical reactions which take place in living cells, and that they are also protein molecules and protein activity is affected by certain environmental factors, WHAT PREDICTIONS CAN BE MADE ABOUT THE EFFECT OF TEMPERATURE ON ENZYME ACTIVITY AND WHY?

2) Starting with 4 test tubes with 5.0 mL of milk in each and 4 test tubes of 1 mL of 0.1% rennet solution in each, and then chilling one pair of tubes in a beaker of ice water for 5 minutes, one pair held at room temperature, one pair immersed in a water bath at 50C for 5 minutes and the last pair in a water bath that 75C for 5 minutes, then working with one pair at a time and adding each test tube of milk to its matching test tube of rennet and timing (using a stopwatch) while rocking the tubes back and forth and watching for signs of curdling to occur within 10 minutes, DOES THE FOLLOWING SEEM REASONABLE?

1) ice bath = 3:40 curdling time
2) room temp = 1:44 curdling time
3) 50C = 24 seconds curdling time
4) 75C = stopped watch at 10 minutes (no curdling occurred as of yet)

3) WHAT WOULD AFFECT THE PATTERN OF CURDLING TIMES?

4) If you change the concentration of one of the reactants so that there are fewer or more of those particles available to react, WHAT CAN YOU PREDICT ABOUT THE EFFECT OF A CHANGE IN THE CONCENTRATION OF ENZYME MOLECULES ON THE RATE OF REACTION?

5) If you were to prepare 4 concentrations of rennin by putting 5 drops of 0.1% "full strength" rennet into one test tube, 10 drops in a second, 15 drops in a third, and 20 drops in the fourth and diluting the enzyme in each with acetate buffer (15 drops in the first, 10 drops in the second, 5 drops in the third, none in the fourth) and mixing each tube with 5 mL of milk and recording curdling time, DOES THE FOLLOWING SEEM REASONABLE?

1) 5 drops 0.1% rennet + 15 drops acetate buffer = 6:05 curdling time
2) 10 drops 0.1% rennet + 10 drops acetate buffer = 7:16 curdling time
3) 15 drops 0.1% rennet + 5 drops acetate buffer = 3:09 curdling time
4) 100% rennet = 3:42 curdling time

WHY DID THE RESULTS COME OUT THIS WAY?

6) WHAT PREDICTIONS CAN BE MADE ABOUT THE EFFECT OF A CHANGE IN THE SUBSTRATE CONCENTRATION ON THE REACTION RATE? WHY?

7) If you had 4 test tubes with the following (1) 10 mL of milk, (2) 8 mL of milk + 2 mL demineralized water, (3) 6 mL of milk + 4 mL demineralized water, (4) 4 mL of milk + 6 mL demineralized water and added 2 mL of 0.1% rennent solution to each tube of milk and timing the reaction rates, WOULD THE FOLLOWING SEEM REASONABLE?

1) 100% substrate concentration = 2:17 curdling time
2) 80% substrate concentration = 2:13 curdling time
3) 60% substrate concentration = 2:04 curdling time
4) 40% substrate concentration = 1:48 curdling time

8) WHY ARE THE NUMBERS GOING DOWN AS THE SUBSTRATE CONCENTRATION GOES DOWN, RATHER THAN UP?

9) THIS DOES NOT APPEAR TO FIT THE PATTERN OF THE EFFECT OF A CHANGE IN THE SUBSTRATE CONCENTRATION ON THE REACTION RATE, WHY NOT?

10) WHAT PREDICTIONS CAN BE MADE ABOUT THE EFFECT OF A HEAVY METAL ION ON THE ENZYME REACTION? WHY?

11) WHY WOULD ONE TEST TUBE OF 5 mL of milk with 1 mL of 0.1% rennent solution with 5 drops of 0.1 M mercury (II) chloride in a water bath for 5 minutes, curdle at 10+ minutes, whereas the same thing but without the Hg2+ curdle within 32 seconds?