Experimental design lab

Purpose: To experiment and observe the changes in reaction rates when pH is manipulated with regards to enzymatic reactions

Hypothesis:   I  will be testing using glucose test strips , lactase enzyme ,test tubes ,milk , and pH standardized solutions ( pH 3,5,7,9,11).  I predict that lactase will function best at PH 6~7.4 given the fact that the PH of the small intestine is around 6-7 .

Materials:

6 Glucose test strips

Lactase enzyme

6 Test tubes

Test tube rack

Milk (pH 6.6)

Standardized solutions (pH 3, 5, 7, 9, 11)

Procedure

  1. Label the test tubes with the corresponding pH.
  2. Fill 1 test tube with 20ml of milk
  3. Fill each of the remaining test tubes with 10ml of a different pH solution and 10ml of milk.
  4. Add 2 drops of the lactase enzyme to each test tube.
  5. Stir to each test tube to mix the solution with the lactase enzyme.
  6. Check each solution with the glucose test strip to determine the numerical value of glucose detected.
  7. Graph the data collected and draw the line of best fit.

Data:

pH Milk (pH 6.6) pH 3 pH 5 pH 7 pH 9 pH 11
g/dL 1/2 Negative 1/4 1/2 1/10 1/4
mmol/L 28 Negative 14 28 6 14

Observations:

The glucose strips changed colour according to the pH it was tested in. The glucose strips that were tested in the pH solutions closest to milk pH were the closest in colour. The glucose strips that were tested in the pH solutions that were the further away from milk pH ( more acidic pH) showed a negative result and no change occurred.

Analysis:

What our positive results are telling us is that lactase broke down the sugar lactose in  The milk. It shows that lactose digestion was most effective between pH 6.6 – pH 7. Our observations and results indicate that lactose digestion was not effective in a solution with a very low pH (pH 3) nor was it effective in higher pH either (pH 9 & pH 11). This tells us that the ideal pH for breaking down lactose is between 6.6 – 7.

Conclusion:

Our hypothesis proved to be correct in which pH lactase works best in.The milk in our control test tube and the third tube which contained pH 7 have similar results and proved lactase to be most effective in that range. Our results show that lactase is not effective In extreme pH whether it be very acidic or very basic. A happy medium was found to be at around pH 6.6~7.4 . The pH of the small intestine is around 7.3 giving rise to ideal pH conditions for lactase to break down the lactose found in milk and other diary products .

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