User:Noy Kaufman/Notebook/Biology 210 at AU

IDENTIFYING ALGAE AND PROTISTS July 2nd, 2015

Purpose:

Scientists began classifying organism that are visible to the naked eye into groups, however, after the microscope was invented, scientists were able to observe microscopic organisms and identify and classify them into different groups. There are two major group that will be discusses in this course: prokaryotes and eukaryotes. Prokaryotes are organisms that lack member bound organelles or nucleus and eukaryotes are organisms with a membrane bound organelles and nuclei (Bentley, Walters-Conte, Zeller, 2015). Each of these groups are made up of different lineages. The purpose of this lab is to identify organisms in a sample from the Hay infusion using the Dichotomous keys.

Methods:

The jar containing the Hay infusion was retrieved and its characteristics, such as smell were recorded. Two samples were taken from two different niches; one sample from the surface of the liquid and another sample was taken from the bottom of the jar near a plant. Two wet mounts of each samples were prepared and observed under the microscope. Three organisms were identified using the Dichotomous key. The identified organisms were then recorded and measured. Next, serial dilutions for the next lab were prepared. Four tubes containing 5 mLs of series broth were labeled 10^-2, 10^-4, 10^-6, and 10^-8. The Hay infusion jar was mixed and 50μL were retrieved and added to the 10^-2 tube; this is a 1:100 dilution. The tube was mixed. 50μL from the 10^-2 tube were retrieved and added to the 10^-4 tube; this is a 1:10000 dilution. This procedure was repeated for the 10^-6 and 10^-8 tubes. Four nutrient plates were labeled 10^-3, 10^-5, 10^-7, and 10^-9. 100μL of tube 10^-2 content were added to the 10^-3 plate, 100μL of tube 10^-4 content were added to the 10^-5 plate, 100μL of tube 10^-6 content were added to the 10^-7 plate, 100μL of tube 10^-8 content were added to the 10^-9 plate. The samples were spread on the plate using a sterile stick. The same procedure was repeated for four tet+ plates(starting with the 10^-9 dilution) (Bentley, Walters-Conte, Zeller, 2015).

Figure 1: serial dilutions diagram

Results and Observations:

The Hay infusion: the culture had a foul, mold smell. There were observable mold brown spots on the surface of the liquid. About 3/4 of the mixture was cloudy and dirty liquid and 1/4 was a thick layer of dirt in the bottom of the jar, which also contains a small plant.

Top sample, surface of the liquid:

Euglena (protozoa): measured to be 40 micrometer. This is a small, green organism, very motile due to its flagellum and is photosynthesizing.

Figure 2: Euglena observed under microscope in 10X.

Chlamydomonas (protozoa): measured to be 7 micrometers. This is a very small organism, it is colorless and is motile due to its two flagella. It is photosynthesizing. Figure 3: Chlamydomonas observed under microscope in 40X.

Didinium (protozoa): measured to be 20 micrometers. It is colorless with two visible bands, a darker one and a clear one. It is not motile and non photosynthesizing. Was present in high quantities. Figure 4: Didinium observed under the microscope in 10X.

No organisms were found in the second sample from the bottom layer of the Hay infusion.

If the Hay infusion culture grew for two more months, I would expect an increase in the number of organisms on the surface and an increased growth of mold. This is due to the fact that the organisms on the surface can get light and oxygen more easily than the ones in the bottom of the culture. The organisms in the bottom of the culture will not get the oxygen and nutrients needed for their development and they will die. Moreover, since the jar is open, new organisms are able to enter the culture reproduce, as a result it is possible that a new ecosystem will be created. Some factors that could affect the community are: lack of oxygen, lack of sunlight, temperature of the room, new organisms introduced to the community, sold surface on top of the liquid, lack of nutrients and fresh water.

Discussion:

The culture has low variability in terms of organisms. The only organisms found were only protozoa and were found on the surface of the culture. Other organisms were identified and most of them turned out to be the same as the ones we identifies before. The sample from the bottom of the culture containing the dirt and plant, did not have any identifiable organisms. This could be due to the fact that organisms that are close to the plan matter might differ from the ones on the surface and have different environmental conditions that were not met in this culture and therefore, they were not able to survive. As a result of the low variability, only three organisms were identified instead of four.

The Euglena found on the surface of the culture fulfill the five requirements of life. 1. Obtaining energy: the Euglena is photosynthesizing organism and therefore obtains is energy from the sunlight. 2. Comprised of cells: the Euglena is a unicellular organism, it is a eukaryote and the same as all living organisms, is comprised of cells. 3. Information: Euglena contains the genetic material in its nucleus. The information in the nucleus is processed to eventually produce the proteins required for the function of the organism. 4. Replication: Euglena reproduce asexually (Freeman, Quillin, Allison, 2014). Reproduction was not observed during the lab. 5. Evolution: this is a very long process that obviously cannot be observed under the microscope. However, all organisms are the product of evolution and Euglena has evolved to its current structure.

References

Bentley, M., Walters-Conte, K., Zeller, N. 2015. A Laboratory Manual to Accompany General Biology II. American University Department of Biology.

Freeman, S., Quillin, K., Allison, L. 2014. Biological science (5th ed.). Pearson: Glenview, IL. 2

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EXAMINING BIOLOGICAL LIFE AT AU June 30th, 2015

Purpose:

Life on earth has evolved to be very diverse. Gene flow, gene drift, and mutations are some modes of natural selection that contributed to the biodiversity and to the expending of certain communities. Large communities, or ecosystems, contain both living organisms (biotic) and non living organisms (abiotic), all of which contribute and affect the structure and characteristics of the ecosystem (Bentley, Walters-Conte, Zeller, 2015). In this lab, a sample from a selected ecosystem, also called a transect, will be analyzed and studied. The different communities within the transect inhibit different niches with different environmental conditions and requirements that are best fit for the specific community.

Methods:

Groups of four people were assigned and each group chose their own 20 X 20 meters transect in the AU campus. My group chose a transect behind Hurst Hall. Once the transect was examined thoroughly, the biotic and abiotic organisms were listed and a detailed map was created and pictures of the transect were taken. A sample containing soil and vegetation was retrieved from a representative area of the transect and placed in a plastic bag. 12 grams of the sample were placed in a plastic jar along with 500 mLs of deerpark water. 0.1 grams of dried milk were added to the mixture and the jar was thoroughly mixed for 10 seconds. The jar and lid were labeled and the jar was left open in the lab for three days until the next lab.

Results:

Our transect is located in the space behind the EQB building and Hurst Hall. The transect was mostly composed of grass and some trees; some biotic organisms that were present in the transect are: grass, trees, flowers, fungi, bees, flies, worms, birds, and squirrels. Abiotic factors included: soil, water, air, light, statues, lams, and sprinklers. Since the transect is located in the borders of the campus, there is a sidewalk and a road right next to it, so there is some human interactions and some traffic around the area.

Figure 1: map of the transect Figure 2: the transect Figure 3: te transect

Discussion:

This experiment was an introduction to the labs to follow. The transect was carefully chosen to meet the requirements and to give a good representation of possible species communities within the AU campus. This transect will be the basis for future experiments regarding the different habitats in it. The Hay infusion prepared will play a role of a new ecosystem for the sample retrieved from the transect. By letting the organisms grow in the new Hay infusion environment we can study the different environmental requirements and conditions of the organisms.

References:

Bentley, M., Walters-Conte, K., Zeller, N. 2015. A Laboratory Manual to Accompany General Biology II. American University Department of Biology

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