Lab+Report+5A++-+Enzyme+Experiment

**Biomolecules**
To investigate the effect of temperature on enzyme action
 * Aim**

Most enzyme reaction will occur at 37°C, with little or no reaction at 100°C/ 0°C.
 * Hypothesis**

- Bunsen burner, tripod stand and gauze - 3 water baths - Thermometer - 12 test tubes and rack - Measuring cylinder - 4 250ml beakers - 2 white tiles - 2 droppers - Ice - Distilled water - Test tube holder - Stop watch - Goggles - 2% starch solution - 1% amylase solution - 1 M hydrochloric acid solution - 1 M ammonium hydroxide solution - Iodine solution
 * Appparatus/Materials**

2. Add 5 cm3 of starch solutions to tubes A1, B1, C1, and D1. Add 3 cm3 distilled water to D2, and then 3 cm3 of amylase solution into tubes A2, B2, and C2 3. Place A1 and A2 into a beaker of ice water, B1 and B2 into a water bath at 37 °C, and D1 and D2 into another water bath at 37 °C 4. Place C1 and C2 in boiling water 5. Leave the tubes for 10 minutes to allow the solutions in the tubes to reach he temperature of the water bath 6. Pour the contents of A2, B2, C2, and D2 into the starch tube, A1, B1, C1 and D1 next to it. Record time immediately. Keep the tubes A1, B1, C1 and D1 containing the mixture in the respective water baths throughout the experiment and ensure that the temperatures are maintained. 7. After 10 minutes, test the mixture in each tube with iodine solution, on a white tile. Draw a table with appropriate headings and record the results and conclusions. **
 * Methodology**
 * 1. Label 8 test tubes A1, A2, B1, B2, C1, C2, D1, D2
 * Results**
 * Test tube || Contents || Condition of water bath || Iodine test || Conclusion ||
 * A || 5cm3 starch solution + 3cm3 amylase solution || Ice water || Turned blue-black || Starch is present ||
 * B || 5cm3 starch solution + 3cm3 amylase solution || 37 °C || Remained brown || Starch is absent ||
 * C || 5cm3 starch solution + 3cm3 amylase solution || 100°C || Turned blue-black || Starch is present ||
 * D || 5cm3 starch solution + 3cm3 distilled water || 37 °C || Turned blue-black || Starch is present ||

1. Which test-tubes shows that starch digestion has occurred? Give reasons. Test-tube B. Test-tubes A, C and D showed a presence of starch as it turned blue-black when tested with iodine, which shows that starch digestion did not occurred for these test-tubes. Test-tube B however, when tested with iodine, did not turn blue-black, but instead remained brown. This shows that there is a lack of starch in test-tube B, hence, we can infer that the starch has been digested.
 * Interpreting the results

2. Which of the test tubes contained mixtures that gave a blue-black colour? Test-tubes A, C and D.

3. Why did the mixtures in tubes stated in Question 2 remain blue-black? Little or no starch digestion occurred in these test-tubes, therefore the starch was not digested and was detected by the iodine, therefore the mixtures remained blue-black.

4. What purpose does the tube D1 serve? D1 serves as the control for this experiment.

5. Using your knowledge on the structure of starch, describe the test you would use to detect the presence of the substance produced as a result of the reaction state in Question 1 above. The amylase will break down the starch into reducing sugars, which can be identified by the Benedict's Test. The mixture will change from blue (original colour of Benedict's solution) to green, yellow, orange, and finally brick red, which signifies high level of glucose present.

6. What conclusion(s), based on the observations of the experiment, can be made about the effects of temperature on enzyme action? An increase in temperature will cause an increase in enzyme action until it reaches the optimum temperature/maximum point (approximately 37 °C [body temperature] ), where it will abruptly decrease with further increases in temperature.  The rate of enzyme action is slow at low temperature (for example at 0 °C ) because the molecules have low level of kinetic energy and thus collisions between the enzymes and starch molecules are more infrequent. With the increase in temperature, the molecules gain kinetic energy and thus the enzymes collide with the starch molecules more frequently, leading to a higher rate of enzyme action. The optimum temperature is the temperature at which the enzyme action is at its peak (around 37 °C ). After that, however, the heat only serves to modify the shape of the enzymes (denaturation), and thus change the active sites, leading to a decrease in the rate of enzyme action. The rate of enzyme action will decrease until the enzymes are completely (around 65 °C ). **