Sunday, March 08, 2009

bio labs

The introductory biology course I'm taking is designated BIO100. Instead of being a 14-week semester, it's compressed into 8 weeks. Over the course of this 8 weeks there are 6 labs, 5 essay assignments, 2 take-home tests, a mid-term, and a final exam -- that last is coming up quickly, March 21.

I will be so happy when this class is over. I happy to confirm that I do, in fact, love the material. I came into it thinking it would be mostly review, but it has been years (decades, really) since I took a formal bio course, and there have been lots of changes. Last time I studied taxonomy, for example, there were only two kingdoms, not five. It's very cool, learning all this new stuff. It's all very cool studying this stuff at a college level (getting into the nitty-gritty of cellular metabolism reactions, for example) rather than a high school or AP course level. But still, it's a grind, and since I worked three days this week and then went on an all-day field trip on Friday, I was scurrying today to do my lab.

The labs have been fun. Today's was on plant pigment chromatography.

Preparing the chromatography paper with drops of plant pigment

I was happy they gave us enough material to do this lab twice. The first run I used regular red-leaf lettuce which didn't have enough red pigment in it to be at all distinguished from the spinach. The photo above shows my second attempt using red oak lettuce which is totally purple and perfect for this lab. I was sure to use more plant material and more acetone on my second round, and covered the bowls while the pigment was steeping so the acetone wouldn't evaporate as it had in my first attempt. (One thing I didn't like about this lab was the loosey-goosey directions. I would've preferred "cut a two-inch square piece of plant material and cover with 20 mL acetone", then I'd know I was going to get a good amount of pigment in the solution.)

Capillary action at work. This jar contained the acetone solvent.

Results were pretty cool. I should've done the reading first because then I wouldn't have been surprised by how much chlorophyll was in the red oak lettuce. Note the abundance of green pigment on all four strips (2 were spinach, 2 were red oak lettuce; one of each was dipped in water, one of each was dipped in acetone).
Results that look like they came from an actual lab experiment!

Kitchen counter labs have an aura of weirdness about them, at least to me. I think my favorite was the one where I got to see the effect of a recessive gene for sickle cell anemia among a population where malaria was prevalent.
Playing God.

I'd choose a pair of "alleles" (beans) at random from a bag, and if I got two dominant hemoglobin A genes, I'd have to flip a coin to see if the individual got malaria and died. I felt sad every time I had to put a pair of beans into the "non-surviving alleles" bowl. It was sad. The whole exercise didn't even take 15 minutes but it was instructive.

Meanwhile, I'm gardening:

Interesting crop selection, yes?

This was taken a couple of weeks ago -- everything is growing and is at least 2 inches tall by now. It's a shame, really, because I'm about to spray half of them with a selective herbicide for my last lab. After 2-3 weeks of nurturing and hoping the cats don't eat them, I don't really want to kill half of them off, but in science, we have to be tough about these things.


Lexis said...

I am doing the same bio course right now through rio salado. I did the chromatograhy lab, but I had some trouble with it. My water test strips got a little messed up I think. I'm having a hard time with the discussion questions too. I don't know what they mean by "specific pigments."

I noticed this post was in March, but do you think you could help me out a bit?


Lexis said...

my email is