Friday, December 5, 2008
Tuesday, December 2, 2008
The first staining procedure we did for Microbiology lab this semester dealt with the Gram Stain. The stain was, “…named after the Danish bacteriologist who originally devised it in 1882,”is done in order to allow for the classification of bacteria as either gram positive or gram negative, often for diagnostic purposes. The procedure consists of the following basic steps: a drop of primary stain (crystal violet) is applied to a heat fixed smear of the bacteria of interest, leaving all cells stained purple initially. Secondly, the bacteria are washed using distilled water and a single drop of IKI or Gram’s iodine is then applied over the smear so that CV-I complex crystals may be allowed to form. Next, after another washing with distilled water, ethyl alcohol or the decolorizing agent is applied so that the thin outer layer of gram negative bacterial cells is dissolved away, allowing for the loss of the primary stain in this particular type of organism (while the thickly walled gram positive bacteria are capable of retention of the CV-I complex). Lastly, after washing the decolorizing agent off with distilled water, the counterstain, Safranin, is applied so that the gram negative bacteria may be identified or colored by this reddish-pink dye. Therefore, when viewed microscopically, the gram negative cells are expected to appear pink in color (retain the counterstain color, Safranin) since the CV-I complex typically would have been washed out when treated with ethyl alcohol. However, because the cell structure of gram positive cells consists of a much thicker peptidoglycan layer (which allows for greater retention of the CV-I complex), those bacteria which are gram positive are expected to appear purple in color when viewed microscopically.
Monday, December 1, 2008
The second argument was based on the evolutionary importance of preserving biodiversity. By not driving a variety of species to extinction, we allow for the possibility of further evolution. The more species that are allowed to thrive (for a longer period of time), the greater the chance some of those species will be able to give rise to new species. Furthermore, these new species may play crucial roles in the future evolution of the world’s genetics.
The final argument for biodiversity was philosophically based. Essentially, the importance of preserving our Earth’s biodiversity is determined by how humans choose to respond to this crisis we have created. Humans are capable of acting to preserve the biodiversity of the planet and until this understanding is realized, the devastating rates of extinction which we are causing will continue to devastate the planet. I feel the most compelling argument would be the final one since it takes into account the importance of human ethics and morality. It discusses how humans may be heavily swayed by the economic and evolutionary repercussions of our destructive behavior, but what ultimately dictates how we will deal with the situation is our own consciousness.
Within a population, there are bacteria with varying levels of antibiotic resistance; therefore it is easy to determine that the condition of variation is being met. The administration of antibiotic medication results in those bacteria with the genetic capacity to resist termination to survive, while those bacteria lacking the necessary genes for tolerance to the treatment are eliminated. Additionally, there are differences in how a bacterium may acquire its resistance to antibiotics in order to achieve increased chances of survival: transformation, plasmid transmission and spontaneous mutation. Collectively these varied conditions set the stage for natural selection to occur.
Furthermore, once the antibiotic takes effect and bacteria lacking resistance are destroyed, those bacteria which do survive readily multiply and in doing so confer resistance to the next generation. As the cycle repeats, one can see natural selection at work. With so many different possibilities, so many different ways for bacteria to survive and multiply it is evident that the conditions are ripe for bacterial antibiotic resistance to continue evolving through the process of natural selection.