Friday, December 20, 2013

Cell Communication Lab $

Purpose: The purpose of this experiment was to test the % of cells produced with an a-type, α-type, and a mixed culture. The whole concept of the lab was all about cell communication and for this lab it was the mating of yeast cells. The independent variable was the time intervals, and the dependent variable was the types of cells we measured. These cells include single/double haploid, Shmoos, single/double zygotes, and Asci.

Introduction: As explained in the purpose the concept of the lab is cell communication. So for the yeast there were two mating types a, and α and both of these create signaling molecules that bind to the opposite type of cell. The received signal is converted to a specific mating response which in this lab it is mating and the series of steps is called the signal transduction pathway. The three steps of cell signaling is reception, transduction, and response. Starting out with the first step is reception
Is basically just the detection of the signaling molecules. Once the signaling molecule is detected is binded to a receptor protein. This sets up for the last step which is the cellular response. It could be the arrangement of the cytoskeleton or genes being created in the nucleus. For the yeast the cell response was the production of more cells through mating.

Methods: In the lab we observed α-type and a-type yeast cultures, through a microscope, and how they interacted with each other after 24 hours, 24 hours + 30 minutes, and 48 hours. In a class where teamwork and efficiency is required for success, we devised a system to complete this lab with minimal problems and delays. We had two group members view the cultures that were dropped using a dropper on a slide and then covered with a cover slip. Those two members would relay how many specimen they counted, whether it was the single and budding haplodes, shmoo, single/budding zygotes, and asci, to the third group member who would record the information for later analyses (this lab). The forth group member would take the already observed slides with yeast, bring them to the 50% bleach and 50% water bucket, sanitize the slide and slide cover by soaking them in the bucket, and bring them back to the lab group so they could be used to analyze more yeast cultures. That process was repeated multiple times over multiple days.     

(Data observed from alpha-type yeast, on the left, and a-type yeast, on the right.)
(Time 1 is at 24 hours, Time 2 is 24 hours and 30 minues, and Time 3 is 48 hours.)
Graphs and Charts:

Discussion: The data we collected from our “a” and “alpha” samples showed a slight increase in single haploid and budding haploid populations, respectively. Though this was recorded this could be due to a number of reasons such as quality of sample and area observed under the microscope, as little to no increase should have been recorded. The mixed cultures, being a combination “a” of and “alpha” “marinated” in broth for 24 hours showed significant transitions of the existing single and budding haploid cells in to shmoos, zygotes, and asci. That was due to the ideal environment that they existed in during that time. The “a” type and alpha type yeast cells send out pheromones which are recognized by the opposite type. When they receive these signals, the two cells are induced to mate which results in a fusion of the two cells (which is a zygote). From there, they begin budding and reproducing.

Conclusions: The summary of the whole lab was that with more time the yeast had the more cells produced for the a-type and α-type separately however the mixed culture did not really have a huge difference in cell reproduction from our data. What we have experienced that did not go according to plan was that our initial test for the cultures did not really was seen when put under the microscope. We adjusted every thing on the microscope, but in the end there weren't any results the first day of recording data. So what we did in the end was only have 3 data points for each test on the cultures as shown on the graph.

References: N/A

A picture of a mixed yeast culture, taken through the microscope.
The microscope and the tubes containing the sample we used.

Sunday, December 8, 2013

Chromatography & Photosynthesis Lab

Purpose: The purpose of the chromatography lab was to use chromatography to separate and identify pigments and other molecules from cell extracts that contain a mixture of molecules. For the photosynthesis lab, it was to test the rate of photosynthesis in different scenarios. The concepts we were testing was photosynthesis itself and its process of how chlorophyll relates to the color change.

Introduction: Chromatography paper is special paper that is used to separate and identify pigments and other molecules from cell extracts that contain a mixture of molecules. It works by viewing how the solvent travels vertically up paper by capillary action (the attraction of solvent molecules to the paper and other solvent molecules). As the solvent moves up the paper, different pigments are carried up at different rates due to due to their differences in solubility. Photosynthesis is the conversion of solar energy to chemical energy in plants. Plants use that chemical energy to promote cell growth, consume it as a food source, and for other cellular functions. That conversion occurs in the chloroplasts plant cells. The rate at which photosynthesis occurs in chloroplasts depends on the amount of light that plants receive.

Methods: In the chromatography lab, pigments from a spinach leaf were extracted on a piece of chromatography paper and barely immersed in 1ml of solvent. Once immersed, we measured the distances the different pigments in the solvent traveled upward on chromatography paper. In the photosynthesis lab, we measured how the rates of photosynthesis were effected in four cuvettes containing different variations of chloroplasts, when exposed to light. Those variations were unboiled chloroplast (surrounded by tinfoil), unboiled chloroplast (exposed to light), boiled chloroplast (exposed to light), and no chloroplast (exposed to light). Each solution’s absorbance and % transmittance was measured before they were exposed to light. Once measured for the first time, they were placed in front of a light and were removed every five minutes, three times for each cuvette, to be tested for any change in absorbance and % transmittance.

The results of the failed attempt, measured in percent transmittance (photosynthesis lab).

The results of the successful attempt, measured in percent transmittance (photosynthesis lab).

Graphs and Charts:
The failed attempt. The time when each data point was taken is shown by color (photosynthesis lab).
The successful attempt (2nd trial). (On the x-axis, "1.0" refers to the sample of unboiled chloroplasts in darkness. "2.0" refers to the sample of unboiled chloroplasts in light. "3.0" refers to the sample of boiled chloroplasts in light. "4.0" refers to the sample without any chloroplasts). (photosynthesis lab)

Our time intervals for each cuvette  (photosynthesis lab).

Our paper chromatography separating the different pigments (chromatography lab)

Discussion: In the photosynthesis lab we had two trials hence two graphs for our data. As seen above both graphs show different results however one is more accurate than the other due to certain errors and calculations. Going into that we encountered the time for each test being a problem for the first trial as some tests did not meet the time requirements stated in the lab. As such in the 2nd trial we made sure that we had enough time to do all the tests and correctly measure as well the photosynthesis rate. The results of both trials can be contrasted by the scaling of the rate of photosynthesis and also how the 2nd trial showed more of an increase for the unboiled chloroplast in light, which was the one cuvette that should have shown the most progress as time went by. In the first trial it showed a decrease or none at all in the rate of photosynthesis of the 2nd cuvette and that is not suppose to occur. overall our 2nd trial did support what was suppose to happen as the lab stated as we learned to fix the mistakes that affected our results.

Conclusion: We found that there was a wide variety of colors displayed when the chromatography lab was in progress. As the colors showed the solubility of each was shown on the strip of paper. As for the 4b which was the photosynthesis part of the lab, we found out about what went wrong the first time we did the experiment and that was the time for the reaction to occur. Given a time limit when not enough time was given the rate of photosynthesis did not really occur in a situation that was supposed to happen. For example the unboiled chroloplast with light in our first attempt showed no response in the rate of photosynthesis. Hence why a 2nd trial was done to see if there was a huge difference and there was.

References: N/A