This week was focused on moving forward in Unit Four, specifically in cell division. We learned the phases of the cell cycle, the phases of mitosis, the hormones and enzymes that regulate if and when a cell goes into mitosis and divides, and began looking at meiosis, the process by which gametes are formed in sexual selection (4.4). This week was probably one of the busiest of the school year for me, and so, considering that, I think I did pretty well with the work. For homework, we had three vodcasts in Unit 4 to complete, as well as our PCR lab write up. This was a bit of a struggle for me, because I spent a lot of time trying to make sense of and organize all the material from the lab to ensure I included everything I needed to and made sense while doing so. Because of this, I wasn’t able to concentrate on the vodcasts as well as I would have liked to. Usually, if there is something in a vodcast I don’t understand, I won’t move on until I have rewatched it or searched out other material in the textbook or online to help me understand, but with my time being so limited this week, it was all I could do to get the vodcast done and make sure I understood enough to answer the WSQ questions.
We began the week by completing Vodcast 4.5 as homework. It dealt with the phases of the cell cycle and mitosis, and reviewing the terminology associated with cell division, like chromatids vs. chromosomes, centromere, and diploid vs. haploid. I feel pretty comfortable with all of the material in 4.5, as it is largely a review of Adv. Bio, but I will work on solidifying everything, since I didn’t get to take as much time on the vodcast as I usually like to. Among new things mentioned in this vodcast were 1) the addition of “Prometaphase,” a little in-between phase where the chromosomes begin to migrate to the center of the cell and two complete spindles have formed, and 2) a small section of the evolution of mitosis that discusses that there are more similarities between eukaryotic and prokaryotic cells that we usually think. I think I have a good handle on these two new additions, and find them interesting!
Our second vodcast of the week was 4.6, which dealt with regulation of the cell cycle. This is a brand new subject for me, and so I am still feeling a bit uncertain of the specifics, such as which checkpoints are responsible for what, and which hormones and enzymes they employ. What has helped me feel more familiar with this new material is the work we did with the HHMI packet. I still definitely need to spend some more time straightening the specifics though.
Our last vodcast of the week was 4.7, a review of meiosis, complete with that earworm video of the chromosomes doing do si dos. That has literally been stuck in my head all weekend. Anyway, Vodcast 4.7 reminded us what meiosis is, the stages it has to go through in meiosis 1 and 2, and the cell’s progression with regards to being haploid and diploid. One part that we had gone over to an extent, but never this specifically, was how many different gamete combinations are possible. Seeing those numbers was insane, and really made it sink in how incredible meiosis is. I mostly understand everything to do with meiosis when I’m looking at the information, with a few questions on the whole haploid-diploid piece, but I definitely need to spend more time so that I can remember things without having to look at the paper. I think I should be good by simply watching the vodcast again, but if that doesn’t do it, I’ll see if there are any good Khan Academy videos or other online resources, or, of course, ask Mrs. Cole.
Cell division is imperative for life to sustain itself as an individual organism and as a species, so our work this week was crucial to our understanding of biology. Organisms need to heal and grow, so mitosis is important to the survival of individuals, which is important to the survival of populations. Regulating mitosis can mean life or death, because of the mutations that can be passed down affecting tumor suppressors and/or proto-oncogenes. Meiosis is how sexually reproducing organisms are able to continue their lineage and sustain a population or species, and is the reason that we sexually reproducing organisms are all so different. Without these processes, regulated by enzymes and hormones, we wouldn’t have the organisms we have today, nor the variation that is present in them, allowing mechanisms of evolution to act upon populations and shape them.