The main purpose of this laboratory was to identify microbes on three different environments; pond water, hay infusion and yeast suspension, under the compound light microscope.
First, the TA showed the class the rules for handling correctly the microscopes. The different magnification and their purpose were explained as a preparation for the oncoming experiments and the remaining of the semester.
In the analysis of the sample, the group didn’t find any clear example of cyanobacteria and/or eukaryotic algae that could be used to differentiate between them. Even though these two organisms were not seeing during the experiment, the group was able to find information about their main differences. Among the most important different characteristics are the presence of nucleus in eukaryotic and the absence in bacteria, it is also relevant the differences in their plasma membrane and the type and number of organelles present in these cells. Most organism observed during the experiment were of large size and thus easier to see. Two of them are from the Protozoa group (Amoeba and Paramecium), while the other is from the Protists group (Euglena). Other structures that can be observed in these organisms were labeled in the drawings. By placing a cloudy drop of Hay Infusion on a cover slide and making a “hanging drop”, the group was able to determine the difference between Brownian motility and true motility. At first glance, random movements of particles that collide with other organisms or cells present in the infusion were observed; this phenomenon is called Brownian motility. In true motility, the movement is more organized and is due to the movement of the organism that can propel themselves, usually by means of cilia or flagella structures.
After the wet mount of the yeast suspension was placed on the compound microscope, we were able to observe the yeast cells. In which we were able to observe some of the intra cellular structures like the vacuole and the bud. Yeast is a kind of fungi, single cell organism. · During the first part of the lab the TA explained the proper ways to handle the compound microscope. Also, she went over the different kind of magnifications. · In the first exercise, the analysis of pond water was performed in order to identify the different organisms present. We were able to see an amoeba at 10X and 40X magnifications. We also observed a Paramecium and a Euglena, both were seeing at 10X and 40X magnifications. In the case of these two, 40X was better to identify the intra-cellular structures due to their size.· For the second experiment, we did the Hay Infusion in which we were able to differentiate between the Brownian motility and True motility. For this purpose, we used the hanging drop method.· On the third and last experiment, we prepared a new wet mount using a yeast suspension. We used the 40X magnification in order to observe this cell which is really small. Even though the intracellular structures were very difficult to distinguish, we think we may have seeing the vacuole, which is among the more sizable structures.
· I believe the purpose of the lab was met. We learn how to properly use the microscope and at the same time identified different environmental organisms.