Know Your "Cell-f"

The big idea I want to get across is that our cells are essentially a microcosm of us. The things that we need as individual organisms are the things that each of our cells needs individually. The food and oxygen we need to take in, the waste materials we get rid of, the temperature we maintain, and so on. Reproduction takes place ultimately at the level of the cell. I've extended it to the idea of friendship, even. We as individuals depend on our friends and social networks for survival, so too do our cells need each other. No cell is an island, so to speak.

I haven't any particularly new ideas these days and not much in the way of new material - we just did a rinky-dink lab looking at onion and cheek cells under a microscope. It's the kind of lab that I despise but I needed a filler as I don't have an alternative yet. As I've mentioned before I like labs where students are trying to answer a question by measuring or otherwise collecting numerical data and I don't have anything that involves making a wet-mount slide and then looking at the cells for some variation that we can quantify and correlate to another variable. I can think of some possibilities but I haven't had time to sit down and test them out or develop a lab around them.

One idea is to take for example a green onion and look at the different parts of the onion - root tips, bulb, green tips - to see if there is variation in the average size of the cells in these different parts (I'm pretty sure this is based on another lab I've seen somewhere looking at the different stages of mitosis in the different parts - but that requires complicated staining techniques if I remember correctly, or prepared slides). My reasoning is that parts that grow faster (root tips?) will show a smaller average size because there will be more of them at different stages of mitosis - the daughter cells initially being smaller than the parent cells. How would we measure the size? I noticed in our labs that 100x magnification of onion cells gives us a nice, easily countable number of cells within the field of view. A greater number of cells within a given field of view means a smaller average size obviously. If you've done this kind of lab or know of links to a version of it on the web I'd like to know. I could be totally off and there are probably other variables that affect the size of cells in the different parts of the onion that would make a conclusion impossible to draw, so I would really need some time to go through the lab myself to see if it's feasible.

On to human body systems and maintaining homeostasis.