Biology

Lab 4: Enzymes

5 Points

In this lab exercise, you will work through a virtual lab on enzymes. The link for the lab activity can be found below. After clicking the link, you will need to read through the ‘overview’ and ‘effect of pH’ tabs on the left side for background information. You can read through the other background tabs below those for additional information.

https://www.ucl.ac.uk/~ucbcdab/enzass/enzymass.htm

1.) Click ‘RUN the program’ on the left side. Next, click ‘save file’ and open the file on your computer. You will design 2 experiments. Remember that each experiment can have only 1 thing tested/changed. You can test the effect of pH, temperature, amount of substrate, etc on the enzyme activity. When you have run your 2 experiments, pasted a screenshot of them below and briefly describe what you tested and what you found. This is your chance to play around with the simulation and see how different conditions affect enzyme activity (1 point).

2.) Imagine that I am going to test the effect of pH of the activity of an enzyme called lactase (this is the enzyme found in the human body that breaks down the lactose sugar in milk). I tested 5 different pH levels (listed in the table below) and measured the amount of product formed.

pH	Amount of product that formed (g)
3	20
5	150
7	300
9	130
11	15

a. What is the independent variable in this experiment? What is the dependent variable? If you were doing this experiment in the lab, what variables would need to be controlled? (1 point)

b. Create a graph of the data in the table either by hand or in a program like excel and paste it in the space below. Be sure to follow all of the rules of graphing. (1 points)

3.) I tested the effect of 5 different pH levels on lactase activity. Which of these samples were acidic? Which were basic? Which were neutral? Based upon your results, what is the optimal pH for lactase activity? EXPLAIN how you know. Why are these findings important? Hint: think about the pH of the human body. (1 points)

4.) Now imagine that you could be in lab and you want to determine the optimal temperature for lactase activity. Design an experiment to test this. In your design, state your hypothesis and a step by step method that you would use to test your hypothesis. Think back to all of the variables of a scientific experiment from lab 1. What will you measure? What will you control? How many replicates would you do? Be thorough in your answer! (1 point)