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Foxs-In-A-Trenchcoat t1_j3iu4of wrote

Reply to comment by ihaveredhaironmyhead in How does the spindle apparatus know what to do during cell division? by ihaveredhaironmyhead

Your question is more accurately a chemistry question than a biology question. More specifically physical chemistry. It is entirely a matter of molecules bumping into each other. Molecules have different types of surface area made up of different atom types --your carbon, oxygen and nitrogen mostly in biology. There are either favorable "sticky" interactions or unfavorable repulsive interactions with the surface types of other molecules.

Most intuitive example is how oil and water don't mix, that's unfavorable thermodynamics. But sugar and water do mix, that's favorable thermodynamics.

Evolution used these rules to build cells that function. If two molecules need to find each other to function, they evolved "sticky" parts that lock together.

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ihaveredhaironmyhead OP t1_j3ixzo3 wrote

This is remarkable to me. I don't know why this isn't talked about more. Every inch of us is composed of cells - yet the function of these cells (you could almost say the function of "you") is entirely a chemical process based on random interactions. The spindle emerging and grabbing hold of chromosomes and arranging them in the middle and splitting them into different sides - this intelligent looking process is fundamentally the same as pouring oil into water. Do I have that right?

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Foxs-In-A-Trenchcoat t1_j3j17c9 wrote

Yes. The laws of physics are always working on the larger scale and the smaller scale. There's a lot of reasons why a car works, internal combustion engine, friction of the tires, blah blah blah, but ultimately it's fundamental physics.

Physical chemistry is the hardest undergraduate level class. There's a lot more to it than oil and water. But oil and water is the reason cell membranes exist.

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