Sunday, April 06, 2008
Slogging along a Path(ology)
(left: Arachidonic acid molecule)
The title is something of a misnomer. Pathology is actually a great class. It uses thing from pharm, micro, and cell bio. This means that I have to dredge up memories from cell bio of things I haven't seen in maybe 6 months. Path is, to use the current pedagogical buzzword, "integrative." We have lecture only once a week, and then gross lab for 90 minutes once a week, and another small group activity for another 90 minutes. This small group activity is far superior to the organized dawdling that was genetics PBL. First, these groups are self-selected, so I only work with people I know work hard. Second, there is not moderator to dampen any collaboration. The moderators in genetics, just by being present and having control of our grades were likely, even without any effort or outward expression, to quell a lot of the error prone dialogue which makes this kind of exercise educational. The absence of a moderator permits us to explore freely and make mistakes, but also to learn faster because we can be wrong and learn from it. The book is a ponderous compendium, but nevertheless a great resource.
In other news, it looks like my summer research project is going to be funded. Do I fully know what I'm going to be doing? hmmm not really. At least they'll pay me to do it though. This week I learned how (sort of) to do a protein assay. The project I'm currently working on is comparing the lipid content of mouse livers from a high fructose corn syrup (HFCS) and trans fat (TF) diet, vs. control of normal chow. In quantifying the lipids, we quantify them relative to themselves, i.e. what percentage of the fatty acids are arachidonic acid for instance. We also quantify them absolutely by comparing them to the protein content of the liver. Since fatty livers have varying amounts of water, using a dry weight/ wet weight comparison is not as accurate as simply using the absolute amount of protein present which is more or less invariate.
To do this, we extract the protein from the protein layer of a liver homogenate. The liver homogenate is basically ground up liver in a solvent, which is then centrifuged. Different cellular components sediment to different layers, which we can remove by pipette. The protein layer is removed and put into an aliquot. We put a known amount of protein into de-ionized water and run it on a spectroscope. The spectroscope bounces light off the protein, and quantifies the amount reflected. This number then is to give an amount of protein present in the sample that can then be compared with the lipid content. Still with me? basically, the process I just described is what I learned to do last week. I don't know that I could do it again by myself, but I would make a valiant stab at it.