Glucose Presence in the Following Solutions
Type of Solution / Prediction: Positive or Negative Glucose Result / Initial Glucose Reading / Final Glucose Reading
Test tube A: milk and enzyme solution / - / 0 mg/DL / 300 mg/DL
Test tube B: milk and water / + / XXXXXXXX / 0 mg/DL
Test tube C: milk and denatured enzyme solution / + / 0 mg/DL / 0 mg/DL
Test Tube D: sucrose solution and enzyme solution / + / 0 mg/DL / 300 mg/DL*
Test Tube E: sucrose solution and water / + / XXXXXXXX / 0 mg/DL
Conclusion:
We used lactase to break lactose down into glucose and galactose in test tubes A, B and C.
Lactase
G Gal + H2O à G + Gal
In test tubes D and E, we used lactase to break sucrose down into glucose and fructose.
Lactase
G F + H2O à G + F
Lactase seems to be somewhat specific as an enzyme. It does not work as well in sucrose solutions as in milk (lactose) solutions, where it can break down lactase into glucose and galactose easier. Glucose and galactose are both six-sided sugars, while fructose is a five-sided sugar. Lactase can break down lactose (glucose and galactose) into its component parts because its shape as an enzyme fits this specific process. It does not work as well on sucrose (glucose and fructose) because of the shape of the molecule, where fructose is five-sided, as lactase’s shape is specifically made to work best on molecules shaped like lactose.
Test tube A showed a positive glucose reading at the end of the 3 preliminary minutes, showing a 300 mg/DL reading. All the rest should have shown no positive within that time, or 0 mg/DL. Though, if given more time, they may have shown a positive reading.
Test tube D* was a fluke as the results were not expected. It showed a positive glucose reading where it should have been a negative, or 0 mg/DL. This could have occurred by human error. This could have happened due to cross contamination, since all class periods were sharing lab equipment. The materials may also have been switched or used improperly, or there might have even been a possible defective test strip for glucose.
The test results were different from the predicted readings, opposite actually, and this is no surprise as it is possible that my understanding of the lactase processes was not clear when the predictions were made.
Ways to eliminate or prevent cross contamination or any other possible mistake are to use different material than other classes and groups or to clean materials, or to repeat labs multiple times before reaching a conclusion.
Glucose and Fructose
Glucose and Galactose
