Prokaryotes

Prokaryotes

Abstract/Summary: Changing our focus from the properties and functions that take place within the cell to the actual cell itself, we observed three specific bacterial types within this lab: Gram-positive bacteria, Gram-negative bacteria, and cyanobacteria. We closely observed the features of cyanobacteria and were able to differentiate them from other bacteria. We specifically observed gloeocapsa, merismopedia, anabaena, and oscillatoria. In addition to this we observed the different characteristics of prokaryotic organisms referring to size, form, color, elevation and texture, which helped us to understand the diversity of these cell types in the kingdom Monera. Through culturing samples from both the toilet and our own mouths, we were able to observe Gram-negative bacteria. We also sketched our two examples of Gram-negative bacteria. Though we failed to observe Gram-positive bacteria, this may have been due to our sampling and staining procedure. Because of the concentration of the sample towards the center, bacteria within this region are hard to see under oil immersion microscopy. If Gram-positive bacteria had been present, it was covered by layers of both Gram-positive and Gram-negative bacteria making it extremely difficult to differentiate while viewing under a light microscope.

Introduction: Most of the experiments thus far in this laboratory have covered many of the functions carried out within the cell such as enzyme activity, photosynthesis, reproduction, and genetics. This experiment gave us a chance to examine the overall single prokaryotic cell in its entirety instead of just the functions it can carry out.

We will encounter 4 groups under the kingdom Monera: archaeobacteria, Gram-negative bacteria, Gram-positive bacteria, and Mycoplasms. We will also examine the diversity of prokaryotic cell types. For example some are pathogenic, causing diseases, while other are saprophytic, breaking down organic material, and further still some bacteria are autotrophs, making their own food through photosynthesis or chemiosmosis (Lab Manual, 2001). We will also examine the characteristics of these prokaryotic organisms such as the visible size, form, color, elevation, and texture of a colony or colonies. To get detailed observations of these various organisms we will view their occurrence through the culturing of samples by adding microbes onto a sterile medium within Petri dishes and allowing them to multiply. Finally we will also examine the features of cyanobacteria that distinguish them from other bacteria, and their role in nature.

Materials/Methods: First examine the plates prepared in the previous week and observe as many of your other classmates plates as possible.