Size limitations in cell biology

So I’m not as well read in biology news as I am in physics news but occasionally I read news in biological research that is just fascinating to me. Extremophile creatures, critters that live in very dry, very hot, very cold or very radioactive environments, fascinate me because they show us the limits of earthly biology. In science, in learning the limits of a thing, you can check the assumptions of your models of that thing. So we can learn a lot about organisms by looking at the very largest examples of that organism and the very smallest examples of it. These will tell us what kind of sacrifices, specializations and optimizing that plant or animal had to do to achieve that size.

For example until 1985, we thought that simple one celled creatures, prokaryotes like bacteria or blue-green algae, couldn’t grow above a certain size due to chemical efficiency limitations in their simple cell structure. But since 1985, we discovered bacteria that grow to nearly a full millimeter in size. These bacteria are large enough to see unaided as they swim and bend in a droplet of water. These creatures show that our old assumptions about size limitations in bacteria were wrong.

But today, I just learned of another creature which is the flip side of that. It’s a species of wasp, a multicellular creature, which is the same size as an amoeba or a paramecium–which are one celled creatures. The fly is barely 200 microns long and the cells that make up it’s body are staggeringly tiny in comparison to other multicellular creatures. This makes it very interesting because we can learn how it manages to make its cells so tiny.

Multicellular creatures usually have more complicated cells in comparison the creatures like bacteria or some species of algae. The cells of complex plants and animals have specialized structures within their cell walls that do specific tasks like metabolize sugar, make proteins or store fat molecules or water. Bacteria, and other prokaryotes, don’t have this kind of specialization.

Anyway, this microscopic wasp evolved along a path where its cells sacrificed some of these special structures, called organelles, in order to get smaller. Its nerve cells have no nuclei like our nerve cells, or the nerve cells of most other multicellular animals do. Stuff like this forces biologists to go back and reconsider some of their assumptions about complex cells and what those cells need to do their job.

This very fascinating to me. That’s why it’s here on my site.

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