Friday, December 20, 2013

Cellular Communication Lab

Purpose: The purpose of this lab was to determine the effects of varied amounts of time on each type of yeast cell. The different types of yeast cells were A type, alpha type, and mixed. The independent variable was the amount of time the cells were left, and the dependent variable was the number of cells left at the end.

Introduction: Yeast cells use cellular communication to mate and form shmoos. Cellular communication is a method that cells use to talk to each other and mate. Specifically in yeast cells, the A type cells send out a signaling molecule specific to the receptor of the alpha type, and this forms a diploid zygote, which then turns into a diploid budding zygote and forms an ascus. An ascus is a mixture of alpha and A type cells. These types of cells  are only seen when a and alpha type yeast cells are mixed together. When on their own, we only see single cells and budding cells.
Mixed a and alpha cells are shown here. This we can see because there are many more cells viewable through the microscopes.

This shows the same mixture, yet fewer yeast cells can be seen. 

This is alpha type at 48 hours.

To begin the experiment, we got culture tubes and labeled them alpha-type, a-type, and mixed. We had 4 mL of sterile water in our culture tube, where then we put a small amount of yeast into each tube and mixed it around thoroughly to make sure all then yeast got into the water.  We were not allowed to use the same pick to get the yeast out for the alpha and a type, but for the mixed we could use either one. Then we went back to our lab table and used a piper to put 5 drops of yeast onto the designated slides. Once again, we couldn't use the same piper for alpha and a type. We put the coverslip over the drops of yeast that was in the slide next. We had to record the yeast at 0 time, 30 minutes, 24 hours and then 48 hours. Once we took out our microscopes and had them all set up, we put one of the slides and focused the yeast using the 10x lens, then once we saw the yeast cells, we changed the lens to objective 40x. Next, we took pictures through the microscope lens so then its would be easier to count all of the cells. We repeated these steps 3 other times per each type of yeast cell. 

First, we have the results for the mixture of a and alpha yeast cells. 
Then, we have the data for each type individually.


Below is the graph for alpha type yeast over time. The two lines depict single haploid cells and budding haploid cells, as per the key above. 
Then, we have the graph for a-type yeast. 
Below is the key for the mixed yeast culture. 

 We had two types of yeast cells, a and alpha, that were pre-labelled for our lab. If we did not know which was which, but we had one known sample, we could determine each type. For example, say we had a sample of a type yeast cells. When we combine it with other a type cells, we will only see single and budding cells. But if it is combined with alpha cells, shmoos would be visible under the microscope. This is because yeast cells have g-coupled protein receptors. In yeast, these receptors can receive signaling molecules from the opposite type of cell. Once this happens, kinases are activated that stimulate the growth of the cytoskeleton in the direction of the signal. This is where shmoos is created. For our results, there were some obvious patterns. First of all, the graphs of single and budding haploid cells for the a and alpha type cells were always inversely related. As one type's concentration went up, the other decreased. For a-type, the last reading could be a mistake. The microscope itself maybe have been too dirty or malfunctioning, but no other cells were visible as the screen was very dark. Looking at the mixed culture, we can see that the concentration of single haploid cells decreases sharply, which was expected. The number of budding zygotes and asci cells increased over time, which makes sense because a and alpha cells will be communicating with each other in the mixture. If they are mixed, then their proximity allows them to receive signals and mate. The only surprising result was that of the shmoos, which we thought would increase over time rather than stay relatively flat. 

The conclusion that we had was that obviously the mixed had a lot more yeast cells than the alpha and a type since it was a mixture of both of them. The other observation that we made was that the more time that elapsed, the less percentage of each cell in the mixed, except for the schmoos. Which could be what was supposed to happen or it could be a calculation error in some way. Also I believe the single haploid was eventually supposed to be less than the budding haploid, because they would all turn into those toward the end. That ended up happening in the alpha type and the a type, but the mixed culture seemed to have some differing results.

1 comment:

  1. For the mixed culture graph, next time spread out the % numbers so the lines aren't all mashed together. How about the lab discussion questions?