User:Ellery C. Spahr/Notebook/Biology 210 at AU
Observing and Identifying Unicellular Eukarya January 29, 2015
Purpose This experiment focused on the studying and identifying unicellular eukaryotes. A dichotomous key differentiated the microorganisms at the surface of the Hay Infusion Culture and from those near plant matter. Every small region of the culture differs in abiotic and biotic features. The experiment, therefore, tested two inter-samples from moss and from the surface of the culture. This reveals which organisms thrive in which environments. When examining samples from Hay Infusion Culture, more microorganisms will live near the plant matter than the surface of the culture.
Materials and Methods • Microscope (ranging from 10x to 40x) • Dichotomous key (a series of morphological choices based on observations of color, shape, length and movement) • Hay Infusion Culture (consisting of soil, plant matter, Deer Park water, and .1 gram of dried milk) • Protoslo (slowed the moving microorganisms, allowing for better focus and identification) • Nutrient agar plates and tetracycline plates • Test tubes • Ethanol and Bunsen Burner (to sterilize the spreader) • Micropipette (to transfer a 100 mL of the Hay Infusion culture to the tubes, and then to the nutrient agar and tetracycline plates)
First, I retrieved samples from the Hay Infusion Culture and placed a few drops on slide for a wet mount. I retrieved on sample from the surface of the culture, and the other from the surface of moss. A drop of Protoslo slowed the motile organisms. The microscope then magnified the microorganisms, which allowed for a thorough examination of color, shape, length and movement. I recorded these observations, and used the dichotomous key to identify organisms.
Then, in preparation for the next experiment, I prepared and plated serial dilutions of the Hay Infusion culture. With the lid on, I gently shook the container to mix the contents. I labeled four test tubes of 10 mL of sterile broth as 102, 104, 106 and 108; I also labeled four nutrient agar plates and four tetracycline plates with 102, 104, 106 and 108 on the agar side of the plate. To differentiate, I labeled the tetracycline plates with “tetra.” I used a micropipette to transfer a 100 mL from the Hay Infusion culture to the 102 tube, and swirled. I subsequently transferred a 100 mL from the 102 tube to the 104 tube, and repeated the process twice more to dilute the 106 and 108 tubes. I pipetted 100 mL of the dilutions onto the corresponding agar nutrient and tetracycline plates. Then, I removed the spreader from the ethanol bath, and then placed it in the flame. Before spreading the dilution on the plate, I allowed the flame to cool. When the dilutions spread across the respective plates, I placed the plates onto a rack to incubate a room temperature for a week. This process prepared the class to examine bacteria species in the culture.
Data The culture appeared light brown, with a distinctive darker brown growth on the surface of the culture and the side of the glass. Green and brown growth appeared on the moss at the bottom of the glass.
Surface
Paramecium Caudatum • Motile • 180 to 300 micrometers • Protist
Colpidium • Motile • 50 to 70 micrometers • Protist
Bursaria Truncatella • Motile • 500 to 1000 micrometers • Protist
Near Plant Matter
Vorticella • Motile • 50 to 75 micrometers • Protist
Paramecium Aurella • Motile • 120 to 180 micrometers • Protist
Chlamydomonas • Motile • 5 to 12 micrometers • Algae
Chlamydomonas can be characterized as form of isogamous, unicellular, motile algae. Chlamydomonas meets the requirements of life because: It replicates through asexual reproduction, when two cells function as isogametes. Composed of cells, it contains chloroplasts that allow it to photosynthesize and acquire energy. Scientists consider it the origin of multicellular evolution in the Volvocine line.
Conclusions and Future Directions Different species grow in different niches of the culture. More oxygen exists at the surface, and perhaps the microorganisms at the surface require more oxygen. In the future, more unicellular eukaryotes would likely reproduce.
E.S.
Observations of the "Marsh" at American University January 25, 2014
Purpose This experiment observed and tested a 20 by 20 meter transect at American University. Inspecting this niche offers insight into the abiotic and biotic components, which may have symbiotic or competitive relationships.
Materials and Methods First, I examined the assigned transect for thirty minutes. This transect sits approximately 30 feet from the Kogod School of Business, and 50 feet from the Massachusetts Avenue. Through the course of this examination, I drew a topographical arial map [attached]. I then collected 50 mL of soil and plant matter. An estimated 50 percent of the collection contained soil and 50 percent plant matter, such as moss and grass. During this collection, the temperature in Washington, D.C. fell between 35 and 40 degrees Celsius.
In preparation for the next lab, I prepared the Hay Infusion Culture. First, I measured 10 to 12 grams of soil and vegetation from the "Marsh," as well as 0.1 grams of dried milk. I then added this sample to 500 milliliters of Deer Park water, and gently shook the jar for ten seconds. I removed the top of the jar, and allowed organisms to grow in the culture for a week.
Data and Observations The transect appeared to be on relatively level ground. Tall stalks, sedimentary rocks, dry bushes, and grass cover a majority of the transect. The man-made elements were not immediately apparent but upon further inspection, I located a metal grate and a plaque. The transect contained other abiotic (non-breathing components), such as the sedimentary rocks, the soil, plastic and snow. However, the transect also featured a number of biotic (live) components such as bushes, grass, moss, stalks of wheat, and insects in the soil.
Conclusions and Future Directions I will periodically monitor the transect, to examine any changes in the niche. As the weather warms, I predict a rise in biotic organisms. This may be an increase in wildlife, such as squirrels or more insects.
E.S.
January 21, 2014
Current (extant) organisms originated from a single ancestor, which evolved and diverged from natural selection.
E.S.
