09/20/28

Trent McMillan

Lab 5: Experimental Design and Serial Dilutions:

Objective:

There were three different objectives pertaining to the lab this week. The first being the collection of soil from around trees along the creek near the BSB. We collected this soil to use in later labs as we conduct experiments and research on the ciliates that live right here on campus. The second objective was to learn about and perform serial dilutions: using micropipettors to dilute a solution in order to find the concentration of cells within a solution and break down the overwhelming amount of cells in the original solution to make it easier to observe a single cell. Performing serial dilutions is an important skill that will be used heavily as we experiment our ciliates as well as in labs to come. The last of the objectives for this lab was experimental design, where we, in our new research groups, got together and set up our procedure and basis for the research and experiment we will be conducting on ciliates. This pertains to making a falsifiable hypothesis that can be tested and replicated by other scientists. Experimental design is important throughout all of science, as it is the first step to every experiment (and eventually solution) of any scientific question.

Procedure:

-Soil Collection

1. Go to your section’s designated area along the creek near the BSB and collect soil (half of a sandwich bag) from the rhizosphere of a Bald Cypress tree.
2. Bring the soil to the lab to label, weigh, and store your sample in the fume hood for use in a later lab.

-Serial Dilutions

1. Observe the characteristics and activity of the given Tetrahymena solution in a 24-well plate through a dissecting microscope.
2. Using the 1000 μl micropipette, put 900 μl of media in each of 4 wells in the same 24-well plate as the given solution.
3. Label each well, starting with 10^-1, ending with 10^-4, putting 100 μl of the original solution directly into the 10^-1 dilute well first.
4. Mix the solution around in the well, then take 100 μl from the first dilution and put it into the second, then from second to third, then from the third to fourth.
5. Decide which diluent has the most countable cell concentration and transfer 5 μl of it onto a concave slide.
6. Observe the slide through a 4x and 10x magnification compound microscope and record the number of cells transferred in the diluted  solution.
7. Calculate the concentration of cells in cells/ml: cells/ml=(#of cells/ volume of drop μl)x(1000 μl/ml)x(dilution factor)

-Experimental design

1. Go to the computer lab and get in your new research groups, look for other experiments/research that can help you come up with a hypothesis and experiment of your own.
2. Based on the question your group comes up with, make a falsifiable hypothesis (that can be tested and proven wrong or right).
3. Design the experiment of which your group will be conducting, include your control and testing variables.

Data:

-Soil

-Serial Dilutions

Due to time being short, I only got the chance to observe the 10^-2 dilution through the compound microscope. I chose this dilutions because it was the most observable after looking at all of them through the dissecting microscope.

-Experimental Design:

• Experimental question: my group and I came up with the question: How do microplastics effect the metabolism/function-ability of Tetrahymena?
• Hypothesis: When introduced to microplastics, the rate of growth/metabolism in Tetrahymena is slowed or stunted, causing the death or lack of production of  Tetrahymena.
• Experimental Design: Using a 24-well plate, we divide the plate into three sections of 8. In the first section, the control group, we will put only Tetrahymena and food for them to live on. The second section, the first testing variable, we will put colored microplastics and Tetrahymena without food for 24 hours to observe how the Tetrahymena reacts/intakes the microplastics. And in the third section, we will transfer the food deprived, microplastic effected Tetrahymena from the second section into it with food for them to eat. We will then be able to observe how the Tetrahymena eat and digest the food with microplastics in their system. We will record the development of each section weekly for as long as time permits to see if our hypothesis is correct.

Storage:

We stored our soil samples under a fume hood, we will leave them there to dry out and cyst until we re-hydrate them for our experiment. All of the pipette tips were disposed of properly in the trash and the micropipettes were put back onto their holders. We put the covers back on our dissecting and compound microscopes and put them back into the center of the table where they belong, and we cleaned off the slides of which we used to observe our dilutions. We put the 24-well plate to the side of the table for our instructors to depose of/store properly. We put the unused tools (such as pipette tips) back where they belong in the side drawer and we made sure our table was clear and clean. Once finished in the computer lab we logged off of the computer properly and made sure to pick up all of our materials that we had brought in there with us.

Conclusion:

In conclusion, we finally got to start on our way to creating our own experiment and conducting our own research just like real scientists do everyday. We are building a great basis of skills (such as serial dilutions, micropipetting, etc.) that will help us with these experiments as well as in the future, skills of which are a necessity to conducting scientific research. Collecting our soil and observing it is just the start to our researching lives that will be full of ciliates that we are beginning to research now. Learning about experimental design and getting to design our own experiment has been a fun, motivating, aspect of this lab so far, and I can’t wait to see the results we each get out of our personal experiments.

Future steps:

In the future, with our research groups, we will get to conduct our own research with our own experiments, which is something many of us have been dreaming about doing for a while now. Although we aren’t researching something like cancer itself, we are getting to research an aspect of science that could lead to discoveries of solutions for many world problems like cancer.  We are literally going to the root of all living cells, and experimenting how some of today’s decisions will impact the world that future generations will grow up in. We may only be doing a small part, but we are getting the opportunity to contribute to scientific studies that could impact the whole world. Once we get this experiment going, we will continue to rebuild and re-test our hypothesis, either proving our hypothesis to be false or correct.