Tuesday, December 11, 2007
Cancer? No thanks!
Plants have cells, chromosomes, hormones, and most of the cellular organelles as animals, yet plants apparently do not get cancer, which is kind of strange.
Plants cannot survive without the sunlight that gives humans skin cancer. So, how come we have cells that proliferate out of control and plants don't?
Plants have a complicated collection of pigments that handle excess energy in solar radiation. That may protect underlying cells from having their DNA blasted and ionized.
Radiation will kill plants. But not give them tumors.
Plants do get things called "galls" but galls are caused by viruses, insects, nematodes and other kinds of parasites. The gall is a way for the plant to hold its enemies at bay.
If humans behaved more like plants physiologically, we would grow a tough container of cells around tumors. Of course, part of what makes cancer perplexing is that it is our own cells out of control. Normal cells would recognize the abnormal ones, but as we know, will not kill them all, all of the time.
Why doesn't yeast develop cancer? Suppose one yeast grew a duplicate, and the "daughter" had damaged genes and would not separate? And then the daughter starts to make messed up yeast cells like crazy. They grow into a relatively big clump.
There is no "central yeast" so the mutated yeast could multiply until it ran out of food. No yeast cancer.
Do we even know if insects get cancer? Generally they are not around long enough to accumulate a cancerous number of mutations.
No, only big animals with a lot of cells get cancer.
Maybe that's the evolutionary price we pay for having trillions of cells. Sometimes one of them goes berserk and makes billions of crazy copies.
In return we get eyeballs, brains, bones, and the rest of the stuff. Respiration, metabolism, the Krebs cycle, and so on.
Would you rather be a plant?