Cellular Communication Lab

Purpose:

The purpose of this lab was to see the effect of time on the mating on yeast cells. The dependent variable which was controlled was time. Yeast was kept for 30 minutes, 24 hours, and 48 hours. The independent variable was the number of yeast.

Introduction: 

Cells communicate through signals that can either be local or long-distance. Signal transduction pathway is a series of steps in which a received signal is converted to a specific cellular response. There are 3 stages in cell signaling: reception, transduction, and a response. During reception, a target cell detects a chemical signal when the signaling molecule binds to a receptor protein. There are 3 major types of cell-surface transmembrane receptors: G protein-coupled receptors, receptor tyrosine kinases, and ion channel receptors. During transduction, the receptor protein is changed and the signal is converted to a form that leads to a specific cellular response. The multiple steps in transduction leads to amplification of the signal. 2nd messengers, such as cyclic AMP can also play a role in signal transduction pathways. Finally, the cellular response is triggered by the transducer signal. Cells of the yeast saccharomyces cervisiae, find their mates through chemical signaling and then initiate the mating process. The 2 mating types of yeast, a & alpha, secrete factors that bind to the receptor proteins on the other type of cell. When these factors bind to the receptors, the 2 cells grow toward each other and fuse together. The new a/alpha cell contains all of the genes from both cells.

Methods: 

Yeast was obtained and dropped into three tubes of water. The tubes were labeled with alpha type, A-type and mixed. Different  yeast was added to each tube, and a mix was added to the tube labeled "mixed." A reading was taken right away and yeast cells were counted. After 30 minutes, yeast cells were counted once again to see the reproduction. This was repeated once again after 24 hours and 48 hours. The yeast was  split into three groups: alpha, a-type and mixed.  Single haploid cells, budding haploid cells, shmoos, single zygotes, budding zygotes, and asci's  were the type of cells that were accounted for under the microscope. After each slide was used and counted for, the slides were cleaned in bleach, in order to sterilize and zap the yeast to its death.   

Data:

Graphs:

Alfa type

A type

Mixed type

Discussion:

Trying to count each individual cell was ridiculously difficult. So we divided each slide into quadrants in order to try to effectively get the most accurate count, then we multiplied each quadrant by 4. This still produced inaccurate results because it was very hard to actually get an accurate count of the cells. This is an example of why.

As one can see it is incredibly difficult to count these cells and especially with the given amount of time we had. We simply could not count them fast enough to get an accurate reading. But from our data one can conclude that starting on the initial time the single haploid cells were more numerous than the budding haploid cells, but then the numbers were reversed at about 24 hours. Where there was more budding haploid cells than single haploid cells, but then the numbers of budding cells reduced again probably because of the reduced amount of space to divide and the cells were sending messages saying that they are running out of room and to stop reproducing. That is what can be observed from the Alfa and A types. Where in the mixed culture the number of single haploid cells becomes reduced over time where the number of budding zygotes and asci increase as time passes.

The experiment could have been improved and made more accurate if we had more time to count and been able to easily take pictures of the cells so that they wouldn't be moving and increasing to the difficulty of the counting.

Conclusion:

As one can conclude from the data the a and alfa cultures had a majority of single haploid cells but then as time passed more budding haploid cells were made, but as more time passed the budding haploid cells had begun to recess and at the end there were a majority of single haploid cells. And in the mixed culture as time passes the single haploid cells are reduced and the concentration of of zygotes and asci are raised.

Photosynthesis Lab

Photosynthesis Lab

Purpose: the purpose of this lab is to prove that chlorophyll and chloroplasts are used in the production of oxygen in plants. Denaturation of spinach proteins were tested to show that chloroplasts were no longer useful when denatured. The independent variables were the drops of DPIP which were used to show that chlorophyll was actually functioning. The dependent variables was the light,as in the control sample we were able to completely block off all the light which was supposed to enter the cuvette with a piece of aluminum foil. We were also able to change the state of the spinach by using it either boiled or raw.

Introduction:The equation for photosynthesis is 6 CO2 + 6 H2O -> C6H12O6 + 6O2. Photosynthesis has 2 parts: the light reactions and the Calvin cycle. The light reactions occur in the thylakoid membrane, where water is split and oxygen is released and ATP and NADPH are produced. The Calvin cycle takes place in the Stroma and is powered by the ATP and NADPH produced by the light reactions in order to fixed CO2 into sugar. The function of the plant pigments is to absorb light and reflect it to  the reaction centers during the light reactions. The relationship between light intensity and photosynthetic rate is directly proportional so the rate of photosynthesis increases as light intensity increases up until a certain point.  

Methods:  starting off the experiment, each of the cuvettes were filled with a spinach solution, either raw or boiled. DPIP was added to them as well, which was there to be eaten up by the chlorophyll as light reactions would function. If the DPIP was not eaten up and the solution remained blue, the chloroplasts did not function. A control cuvette used to recalibrate the sensor was made the same way as the previous cuvettes with the raw spinach, but it was wrapped in aluminum foil to prevent any sort of light from reaching the chloroplasts. Each of the cuvettes was left in the light for same amount of time, (5,10, and 15 minutes)  and in the sensor for the same amount of time as well. This was to make sure everything was tested equally to provide us with the most accurate results.  

Data:

First Trial

Second Trial

Graphs:

Discussion:

The first trial that we did there was no change in the color because we did not put enough Dpip into the solution because all the Dpip was used up right away and it was impossible to tell the difference over time. So we increased the concentration of the Dpip in order to be able to better see the change in Dpip used. In the experiment one can determine the amount of Dpip used because the translucency in the solution will become closer to 100%. Ans when The Dpip is not used the colorometer will read something less than 100% because the bluish tint will bring down the translucency.

Conclusion:

As the graph shows, the unboiled light and the unboiled dark were the only solutions to significantly increase in the translucency. the unboiled light was as predicted because it would be the only one that the chloroplasts will be using the light to consume the Dpip. And the only logical reason we can think of why the unboiled dark increased in translucency is because during the short time where we took the sleeve off and put it in the colorometer the chloroplasts activated and consumed the Dpip. 

Resources:

Campbell biology ninth edition