Purpose: The purpose of this lab was to see how growth signifies that cell communication occurs within a population during each stage of their cycle. We were able to see this growth as the populations multiplied over time
Introduction: Yeast is a unicellular organism. The cell of the yeast break down sugar into ethanol during alcoholic fermentation. It also can undergoes asexual and sexual reproduction. During sexual reproduction, the yeast cell change from single haploid cell to a gamete (sex) cell due to a certain chemical signal. There are two types of yeast cell: a-type and alpha type. Each type of cell secrete a mating factor that bind to the receptor on the other cell type. A factor would attach to alpha-type cell receptor. Alpha factor would attach to the a-type cell receptor. When the mating factors is attach to each of the cell, the two cells begin to fuse together to form a pear-shape gamete cell called shmoos. The two cells then finally come into contact to form a single cell that contain gene from a and alpha cell. When the condition is right, the cell will begin to divide during mitosis. The process that the yeast go through can be found in other cell. Yeast cell mate with each other. This is how yeast cell communicate with each other. Cell can communicate with each other by sending signaling molecule to the other cell which response to a particular signal. The cell response can be anything like mating or creating a new protein. Before signaling molecule can send signal to the cell, the signaling molecule have to bind to a receptor on the cell plasma membrane. When a signaling molecule bind to a receptor, like G protein-coupled receptor, it activate the receptor. The receptor then bind to G protein to activate it. This cause the GTP to displace GDP. G protein then diffuse across the cell to bind to the enzyme, causing it to activate. The activated enzyme then send a cellular response. Signaling molecule is then disassociate from the receptor. G protein then disassociate from the enzyme. GTP then turn into GDP. The cell is then able to reuse the G protein. Cellular communication then occur time after time like a cycle to produce many responses that are important to the cell.
Methods:
In this lab, we used 3 types of subcultures: a-type, α-type,
and mixed, which contained the a-type and the α-type. We transferred a small
amount of each yeast type to the water in the culture tube. We used toothpicks
to transfer a clump of yeast 1 mm wide into the designated test tube. After each
transfer we used a new test tube for the yeast. When we finished putting the
yeast in the test tubes, we put 5 drops in the yeast suspension in the plates. After
that we used new swabs when we were spreading the yeast suspension over a small
area of the agar. We then counted the yeast cells by putting them in slides and
looked at them under a microscope.
The three agar jars we used (alpha, A type, and mixed)
Scrapping off some yeast! Ew!
Mixing the yeast to the sterilized water!
Adding the yeast to the trays
Putting it on the slides
The microscope we used to see the slides
Yeast growth (alpha type)!
So many yeast populations (mixed)!
More yeast (a type)!
Data: 
Discussion: As time progressed, we saw that there was an increase in yeast growth. The yeast in our early trials began as single haploid cells and as time went by we were able to see developing double haploid cells and even some single zygotes. This is an interaction directly caused by cellular communication. Since the viles were not stored in incubators, this experiment was done solely at room temperature. As we can see by our graphs and our labeled pictures, all the types were increasing, but the biggest increase in yeast population was seen by the mixed culture. The heightened growth of this specific culture is caused by more (and different types of) yeasts which were able to give off more signals that let the other yeasts know they were present. As a result of this more yeast was produced. Our data is valid because as more yeast communicate with each other it more likely that reproduction will take place. This supported our hypothesis (yeast will increase in number over time) due to the results of the data and 2 graph. We believe our data for the 30 minute section could've been improved because our methods were not consistent. We only added broth to act as a mound for the Petri sample on our the second and third day. Therefore, our experiment could've been more accurate if only we used the broth and maybe did more trials that were closer apart (although our time was limited and was a constraint).
Conclusion: The expected result of an increase in cell population solidifies the fact that communication within the cells in the mixed Petri dish showed a substantially greater increase than the individual a type or alpha type dishes and greater communication occurs when there are various cultures present to send and receive cell signaling. Results could have varied to a massive increase in cell population should the vials have been chosen to be put in an incubator, as cells grow more rapidly in hotter temperatures as opposed to regular room temperature. We had earlier anticipated that the mixed sample would have the greatest increase in population due to it having two different cultures of yeast cells which is exactly what was shown in our graphs. This massive population in the mixed culture was probably on account of both a and alpha type cultures being ble to pruduce a higher level of communication and budding amongst themselves.
