Brianna Belo/Notebook/Biology 210 at AU

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1/21 Lab 1: OWW Introduction

My name is Brianna Belo and I am in my 2nd year here at AU and I am pursuing BS in Public Health, within the College of Arts and Sciences. I work with the Biology Lab at American University. So far I've learned about studying and mapping transects within an environment from the Biology 210 Lab, and I participate in this lab not only because it is a class requirement, but also to gain hands-on learning experience and cultivate my own personal knowledge on the subject of Biology.

1/28 Lab 2: Transect Description


2/2 Lab 3: Hay Infusion and Protist Identification

Initial Hay Infusion Observations The Hay Infusion for Transect 3 had a distinct odor of manure, decay and stagnate water - almost swamp-like. Since the water had been still for about a week there were few dirt particles suspended, instead most of the dirt had collected into the base of the jar, leaving the yet to be stirred product relatively translucent. The water line had receded indicting that evaporation occurred. There was a thin layer of film/growth that had formed on the water's surface. In addition, around the edges of the jar, but on the water's surface, spots of light grey-green mold had begun to grow as well. The Infusion also consisted of plant matter (a branch with a few leaves), and a piece of rotted bench wood. Growth seemed to favor the niches closest to the plant matter, however, there had been some initial algae growth that remained on the bench. Samples were drawn from these niches and from the mid section of jar, consisting primarily of freely suspended dirt particles.


Protist Identification Overall, 3 of 4 samples taken provided produced identifiable organisms. The following organisms identified within the Hay infusion were Euglena, Gonium, Chilomonas, Euglena, and Actinosphaerium. The first sample was taken was from the thin layer of film on the surface of our hay infusion. From this sample we observed small green colored organisms, these organisms had accumulated into a small colony of about 16, indicating that we had found Gonium protists.This sample also contained singular, motile cells, motion of these cells had been achieved through the use of one flagella. In addition these cells were green-brown in color, making them Euglena protists. Our second sample was collected from the center of the jar, which consisted mainly of suspended dirt particles. This sample contained organisms that had collected in relatively large colonies that were brownish in color, when more closely observed it was clear that these organisms were elongated and narrow in shape, indicating that these protists were Chilomonas. The final sample was collected from underneath a section of plant life that had been submerged in the solution. This sample revealed organisms that were colorless and floating with no recognizable motion, according to the dichotomous key these were Actinosphaerium. While Actinosphaerium were described to have radiating spines, these spines were not visible because the microscope was not zoomed into the cells enough.

Image:Transect3Gonium.JPG Image:Transect3Gonium(2).png

The images above depict Gonium, protists that are notable for their greenish in color, and their formation colonies of about 16.

Image:Transect3ChiloandActi.JPG Image:Transect3Chilo.png Image:Transect3Acti.png

The images above depict both Chilomonas and Actinosphaerium protists, both of these organisms are colorless, however Chilomonas are larger and much more elongated than the small, spherical Actinosphaerium.

Conclusions Out of all the organisms identified, the Euglena was the only cell found to be photosynthesizing. The Euglena found were green-brown in color, implying that the cells contained chloroplasts, organelles that enable the process of photosynthesis. [meets needs for ] At the conclusion of the lab, small water samples of 100μL were taken from the Hay Infusion Culture to create a serial dilution. The dilution progressed from 10^-2 of the water sample by increments of two to 10^-8. 100μL of each increment of the dilution was then added to an nutrient agar plate and and agar plate containing an antibiotic known as tetracycline.


2/10 Lab 4: Bacterial Colony Observations

Final Hay Infusion Observation From a final observation of our Hay Infusion we determined that there was more evaporation, as well as growth of a thicker film on top and more mold underneath the surface of the film. Additionally, a stronger swamp-like odor was present and the leaves in the infusion lost their color.

Colony Observations The tet-positive plates had orange yellow colonies that are fewer in number. The colonies were also convex and umbonate in shape. The tet-negative plates had smaller white colonies that were much greater in number, and less uniform in formation. These white colonies also appeared to be raised from the agar plate surface. Lastly, condensation had formed in these plates unlike their tet-positive counterparts. As an antibiotic, tetracycline is expected to help reduce competition for nutrients and other resources. It is composed of molecules that are purposed to either stop bacteria from growing or kill them off. Ultimately the plates with tetracycline produced less bacteria than the plates that did not contain tetracycline, supporting this hypothesis. Concerning Colony Morphology from each sample, both tet-positive and negative, the most recognizable bacteria had small coccus shaped formations. The white tet-positive slides in particular presented hundreds of very tiny coccus shaped bacteria. Overall, the bacteria cells found were so small and all coccus in shape the motility determined was overall immobile, none of the bacteria from the samples had any observed movement.


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