Monday, December 21, 2009

Biology: Why are cells so small?

On the heels of our investigation of cells using the microscope, we addressed the question: Why are cells so small?
In order to answer it, we carried out the following experiment:
We took a whole hard-boiled egg and significantly smaller cubes of egg-white and submerged them in food- coloring. After waiting 10 minutes we took them out, cut them in half, and measured how deeply the food-coloring had penetrated. In both the whole egg and the small egg cubes, the food-coloring moved less than a millimeter in. However, the big difference was when we considered what percentage of the egg had been exposed to the food-coloring. We discussed how cells are limited in size so that they can transport food and other products in and out of the cell efficiently. We also looked at this question mathematically, considering how the surface area and volume change as the sides of a cube increase.

We looked at a few other examples where the ratio of surface area to volume matters. To name a few, cooling off hot water, root systems, and our lungs.

We concluded by making latkas.
What does this have to do with latkas? EVERYTHING!!! Like latkas, cells work best with a high surface area to volume ratio.

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