# I should have loved biology
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But biology, like computing, has a bottom, and the bottom is not abstract. It’s physical. It’s shapes bumping into each other. In fact the great revelation of twentieth-century molecular biology was the coupling of structure to function. An aperiodic crystal that forms paired helices is the natural store of heredity because of its ability to curl up and unwind and double itself with complements. Hemoglobin, the first protein studied in full crystallographic detail, was shown to be an efficient store of energy because of how oxygen atoms snap into its body like Legos, each snap widening the remaining slots, so that it loads itself up practically at a gulp. Most proteins are like this. The ones that drive locomotion twist like little motors; the ones that contract muscles climb and compress each other. Cells, too, are constantly in conversation, and the language they speak is shape. It’s keys entering locks: a protein might straddle the cell membrane, and when a cytokine (that’s a kind of signaling molecule) docks with it, it changes its shape, so that its grip loosens on some other molecule on the interior side of the membrane, as though fumbling a football—that football might be a signal itself, on its way to the nucleus.
.insights Beautiful paragraph. #insights
For a computer scientist, a biologist’s methods can seem insane; the trouble comes from the fact that cells are too small, too numerous, too complex to analyze the way a programmer would, say in a step-by-step debugger. What biologists mostly do is stuff like:
Spin things to 15,000 Gs in centrifuges to separate pieces having different densities.
Separate things of different sizes using gels and magnets. (“Gel electrophoresis.”)
Take one of those gels and blot it with special paper to splay the parts out. Then wash the paper with an antibody that binds to a specific protein. Finally, wash the paper with another antibody that binds to the first one, and fluoresces when it does so. See where the meta-antibody lights up—that’s the protein you were looking for. (I think I’m describing a “Western blot.”)
Use the fluorescent antibody trick to tag cells expressing one or more proteins of interest. Then squeeze the cells through a tube so small that only one fits at a time. As each cell passes by, shine a laser through it to read its fluorescent tags, and use an electric charge to redirect it to a particular bin. Now you can sort and count cells that match your criteria. (“Flow cytometry.”)
Genetically alter microorganisms to make molecular machines to spec; systematically turn off one gene at a time in a cell line and see what changes; edit the genome of a whole animal, and observe its life.