pH and Color of Media

 

 

Objective

·        Develop visual recognition of media conditions which are optimal and suboptimal for cell growth and division.

 

Materials

5 centrifuge tubes filled with media at different pH values (prepared by instructor)

pH meter

 

Safety

1.      Wear disposable latex gloves at all times.

2.      Wear safety glasses at all times.

 

Procedure

NOTE:  You do NOT need to calibrate the pH meter.

1.      Measure and record the pH of each of the 5 centrifuge tubes containing media.

2.      Note and record the color of each of the 5 centrifuge tubes containing media.

 

Questions

1.      What compound in the media enables this colorimetric assessment?

2.      During growth and proliferation, cells deplete nutrients from the media and undergo metabolism.  What are some of the biochemical byproducts of cellular metabolism? 

3.      As cells undergo metabolism, would you expect the pH of the media to increase, decrease or remain the same?  How could a visual inspection of the media assist you in assessing the necessity of changing the media?

4.      Bleach/clorox is added to cells to kill them before disposal.  What, if any, change in color would you expect to see when you add bleach/clorox to cells?

 

Data and answers to questions should be recorded in your laboratory notebook.  The answer to each question is worth 5 pts.