Friday, December 5, 2008

Brown fat

Last Thursday Dr. Ahmad mentioned brown fat during his discussion of various types of metabolism. He asked the class if we knew whether as adults, humans possess this type of fat. Someone responded by saying that, no as adults we do not, but in early childhood, we do. He said that was correct because this type of fat serves as a type of defense mechanism in the very young human being. He described how the brown fat is essential to polar bears of all ages because its properties allow an organism to preserve the energy of their body heat. So the polar bear core body temperature remains at a stable, warm and comfortable level because of this type of fat.
When we humans are very young (infant and toddler age) it can be difficult for us to gauge or sense when our environment is too extreme, (in terms of temperature), or even detrimental to our survival. He gave an example he had heard about some years ago: There was this little Canadian girl who somehow wandered out of the kitchen (where her mother was trying to simultaneously cook and look after her young daughter) and into the bitter winter environment of the wooded area directly outside her home. Once her mother became of aware of her absence, and searched with no avail, she notified the authorities and a search party was mobilized. They spent hours searching and after twelve hours they found her alive thankfully. It is in those extreme situations when the young human body is suddenly exposed to harsh environmental factors that may threaten their survival, that this brown fat is utilized. Dr. Ahmad said he believed that the temporary location of this fat is somewhere around the back of the head or the base of the skull. As we grow and mature we lose this fat so as adults we no longer possess it. Essentially its purpose is outgrown.

Prey defenses & Pop. dynamics

Other prompts given to us by Dr. Baines included the following: “Distinguish between Batesian and Mullerian mimicry and provide an example of each. Describe and provide examples of TWO additional prey defenses against predators.” I wrote, “Batesian mimicry occurs when non-toxic species adapt the colorations of toxic species in order to prevent being preyed upon. An example would be the nontoxic King Snake adapting similar colorations (red-yellow-black striping) to those of a toxic snake species (Coral Snake). Mullerian mimicry occurs when all those species which are toxic appear or adapt to have similar colorations and warn predators that they are all venomous (may be harmful or even a deadly species). An example of this would be toxic wasps or caterpillars all having similar banding patterns along their bodies. Another example of prey defense would be the Behavioral defense of certain frogs who puff up and wail loudly to deter their predators to back away. Also, the body armor of armadillos would be an example of such kind of defense.
She also wanted us to write about this prompt: “Calculate the net reproductive rate [by looking at a table I will explain shortly]. Is the population increasing or decreasing in size? Why? Explain what this means biologically.” The table she referred to in the question contained the values for the variables needed to calculate the net reproductive rate for a population containing three cohorts. I calculated the net reproductive rate to be 0.80 and explained the significance of the value by writing the following: “Population is decreasing in size because since this value is less than one, females are not having enough offspring to even at least replace themselves within the population. Therefore, since no replacement is occurring, ultimately this results in a decrease in population size.”

Potassium and plants

Dr. Baines asked us to respond to the following prompt: “List and provide examples of three approaches you could use to test the hypothesis that increases in potassium lead to increases in the number of seeds a plant produces.” She also wanted us to write a null hypothesis for this experiment as well as identify the independent and dependent variables. My response was as follows: “My first approach would be the Open field approach which would include taking a group of plants into the lab and experiment with exposing them to various levels of potassium while leaving other variables (such as light, temperature) uncontrolled. Then I would record the results.
The second approach would be to conduct a lab experiment. This would include taking a group of plants into the lab and controlling (as much as possible) all aspects of the experiment. Specifically, I would expose the plants to various levels of potassium and record the effect on the number of seeds produced (while controlling pressure, temperature and amount of light received by plants).
The last approach would be to use simple observation for data collection purposes. I would observe how various levels of potassium affect the number of seeds produced in the plants natural state or environment without controlling any of the variables (uncontrolled method).” The null hypothesis would be that the, “potassium does not have an effect on the number of seeds a plant produces.” Finally, the dependent variable would be the number of seeds a plant produces, while potassium level would be the independent variable.

Tuesday, December 2, 2008

The Gram Stain

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.

Making Zen laugh (or trying to)

So I'm supposed to make you laugh, huh? Well here's my attempt: I was sitting there thinking, ‘What would Dr. Faulkes find funny?’ All I could think of was the picture on that slide you kept pointing out. You know, the one of this younger, pasty looking guy sitting on a couch, surrounded by attractive and adoring young women (groupies you could say). I don’t even know why but my mind suddenly connected that to this song I’m ashamed to say I’ve heard my younger brother playing over and over again. The lyrics go something like this: “When I grow up, I wanna be famous, I wanna have groupies…be on T.V., drive nice cars…,” I think it’s annoyingly loud and obnoxiously repetitive, but it made me think of that picture from class. And then suddenly, a weird sort of montage played out in my head and it went like this: Dr. Z (not the mad scientist from some seventies comic series but the unfortunate professor who actually has to sit and read my silly interpretations and commentaries on biological topics) is in a music video with of all people, the Pussycat Dolls (who sing the song I mentioned). In this vision, Dr. Faulkes is dancing around, using moves very similar to those of Michael Jackson in Thriller, when suddenly the Pussycat Dolls appear and begin surrounding him seductively. Then, BAM! Dr. Zen stops his dancing, places his hands akimbo, stares at the gorgeous lead singer of the band, Nicole, (who’s standing right off to his left), then looks directly at the camera and smiles. At that moment Nicole asks him, “Could you please tell me about crustaceans?” He then turns to stare at her again and continues to smile (pleased as punch). But then as he begins to respond, Pam Anderson, (wearing an undersized, ‘I Godzilla [love] Tokyo’ tee), rushes in (because she’s a beautiful Canadian and she can), saying, “No Zen, I want you to teach ME about crustaceans!” A catfight breaks out and again, Zen grins. He is happily amused. Then finally, the scene zoomed out and faded to black as it ended in my mind’s eye. It’s lewd, wildly absurd and over the top (much like dancing ponies) but maybe style point worthy? I hope so. Go Feral Cats, go.

Monday, December 1, 2008


Dr. Baines gave us a prompt just the other day that went like this: “Describe the three arguments for preserving biodiversity in the essay, “Asteroids, Bulldozers, and Biodiversity”.” “The term biodiversity (bio=biological, diversity=variety) did not exist before the mid-1980s.” (Cummings, 2006). The first argument economically discussed how preserving our planets biodiversity is necessary because there are so many species out there that humans have yet to discover. These undiscovered or unresearched species may serve to provide us with resources which could contribute to an increased quality of living for human beings.
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.

antibiotic resistance

The populations of bacteria discussed within the article, “The Ecology of Antibiotic Resistance,” clearly show that there is ‘variation’ in regards to the degree of resistance to treatment. Also, the text illustrates how, ‘individual differences,’ among the bacteria impact individuals’ chances at ‘reproduction and survival.’ Since these two conditions are satisfied one may say the situation is a representative example of evolution by natural selection.

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.