Cell Communication Lab

Purpose

The purpose of this experiment, as the title suggests, was to study cell communication. Our subject was yeast and we tracked it's cell count over fourty eight hours. The controled variable in this experiment was time, where else the independent variable was percent of total cell count. As time passed on, we hoped to see whether the percent of total cell count would decrease or increase- mostly the latter. 

Introduction

Since yeast cells are incapable of moving, they communicate through signaling molecules. These signaling molecules, after being sent by one cell, are received by a G-protein coupled receptor in another cell. The pathway of the signaling molecule can be seen in the diagram below, supplied by Pearson Education. 

The cellular response in this case, is for the yeast cell to grow and divide. In our a and alpha culture of yeast, this will be seen as a budding haploid cell, where else the cells that have yet to receive the signal to grow will be single haploid cells. In our mixed culture, single and haploid cells will be present as well, along with schmoos, and asci. In a mixed culture of a and alpha yeast cells, the cells may recognize each other's presence and beging to grow towards each other- hence what we refer to as schmoos. Asci are bundles of cells growing next to each other, another aspect unique to mixed cultures.

Methods

In this lab, we put alpha-type, a-type, and mixed-type yeast in culture tubes filled with water.  We took samples of 5 drops of the yeast after 0 minutes, 30 minutes, 24 hours, and 48 hours and put them on viewing slides, then examined them with three different fields of view with compound microscopes on a medium 400x magnification. We counted the numbers of single haploid, budding haploid, shmoos, single zygote, budding zygote, and asci cells in each field, then calculated the percentages of each. 

Data Charts

Graph

DISCUSSION

 While observing our yeast through the microscope, no noticeable differences of alpha and a yeast could be seen. Even though they do have different genetic make up. The yeast that were on their own were mating at lower rates than the mixed yeast. In the mixed yeast, schmoos were visible sooner than the individual yeast. Yeast can communicate both indirectly and directly because if some yeast change, then they can send different signals out. When the yeast mate they can receive a signal directly from the opposite gender of yeast cells. Signal transduction pathways combine A and Alpha cells. When A and Alpha cells are together they are mixed. Mixed yeast cells can be haploid, zygotes, budding haploid, or even a shmoo.  When yeast cells mate, they use signal transduction pathways because G Protein receptors help them mate. 

 In our experiment the alpha yeast had more budding yeast cells than the A yeast cells. Our percent totals were approximately the same for alpha and A because they were leaning towards budding haploid cells more. In the mixed yeast cells, since there were A and Alpha, they reproduced sexually. On the other had the individual A and Alpha cells reproduced asexually. The Mixed Yeast cells started with schmoos then by the twenty four hour observation they were haploid cells. Then the haploid cells divided to form asci by the third day. According to our data, as the time went on, many more cells were produced due to reproduction. 

CONCLUSION 

     We are studying Cell Communication in this lab and we controlled the time when we observed the progress of the yeast cells. We observed cellular responses and the growth, then dividing of the yeast. Our percent totals of cell count increased as time when on. Cells communicate with receptors, especially G Protein Coupled Receptors, which aid in the reproduction process. Signal Transduction is also a method for the cells communicate.