Introducion: When only one type of yeast cell is present, either alpha-type or a-type, the yeast will reproduce asexually. However, in a mixed culture, the yeast will signal the other type with pheremones, which the other type have receptors for. This signals the yeast cells to grow towards each other, forming shmoos, and when they meet they reproduce. We measured the amount of cell communitcation happening by counting the shmoos in an area after a partictular amount of time.
Methods and Producers:
In this experiment, we used had three different yeast samples: a-type, alpha-type, and mixed (a combination of a-type and alpha-type). After collecting each from an original culture, we put them in both agar plates and our own culture tubes. In the culture tubes, there was 2 mL of water along with a small clump of yeast. In the agar plates, there was 5 drops of yeast suspension (also know as yeast food). After doing both of this, we would take a forcep to put some of the yeast cells onto a coverslip, so we were able to see the different types of cells that were in the yeast. We first took a reading of the yeast immediately after putting the cells in the agar plates to find single haploid and budding haploid cells in the a- and alpha-types as well as single haploid and budding haploid cells, shmoos, and zygotes. After reading the yeast cells once, we put them into an incubator overnight so they yeast cells could mate and grow more. The next morning we again put bits of the yeast in a coverslip to see if there was difference in a moment of cells there were. When looking at cover slips, we also looked at many different fields of view in one coverslip, by changing where we were looking on the coverslip.
Here is the what the mixed culture looks inside of the microscope. Labeled is a budding haploid, and single haploid cell, a shmoo, and a budding zygote.
Discussion:
The data shows that shmoos would only form in the mixed agar plates and liquid culture, because alpha type and a type can sexually reproduce with one another. In general, the count for haploid, diploid, and shmoo for withon from the earlier time to the later time went up after incubating overnight. Since there were no shmoos forming in alpha or a type, alpha type yeast only has the receptor proteins needed for sexual reproduction and shmoo formation for a type, and vice versa. The incubation helps accelerates growth because the warmth was an ideal environment to grow. As tine passed, more signal could sent from one cell to another, pulling them together and causing the proliferation of yeast cells. Cell communication with pheromones There were problems with data collection and counting the number of yeast cells accurately, so if we were to do this again we would have made it more precise.
Conclusion:
Because no shmoos formed in a non-mixed culture, the conclusion we can make is that the correct receptor proteins must be present, in order to recieve the signal and begin a response. An increase in time also increased the amount of reproduction occurring. Time allowed more signals to be sent, and more responses to be undergone.
