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ihaveredhaironmyhead OP t1_j3icrba wrote

Reply to comment by Foxs-In-A-Trenchcoat in How does the spindle apparatus know what to do during cell division? by ihaveredhaironmyhead

Chemical interactions? I still don't get how the spindles know which chromosomes to grab and what to do with them.

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Evianicecubes t1_j3iekjr wrote

There are protein complexes which identify the centromeres of the chromosomes to be targeted by the spindle apparatus. The protein complexes bind specifically to the centromeres of the chromosomes. Is this sort of what you were looking for?

I think what foxes was saying is that these interactions are passive, not controlled by a nervous system or anything.

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ihaveredhaironmyhead OP t1_j3if5zn wrote

What's another example of a passive interaction? Maybe this would help me understand. To me the entire process of cell division is mysterious. I don't understand how something requiring careful arrangement can be non-neurological.

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Evianicecubes t1_j3ihh1d wrote

I think on a certain level everything happens this way. A virus has no neurological system but it is replicated by a series of chemical reactions. If it doesn’t work it doesn’t continue to exist. Same for cell division. When it doesn’t work the cell dies - or becomes cancer and kills the host.

It is hard to conceive of the fact that this system has evolved by these chemicals literally bumping into each other for billions of years.

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ihaveredhaironmyhead OP t1_j3iq6hm wrote

The information in the DNA is what contains the instructions for our body, correct? Does the DNA also contain instructions for how the cell works? Or is this a separately evolved system that works based on molecules bumping into each other? Can I conceive of the cell as almost a separate life form that exists inside of me?

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Foxs-In-A-Trenchcoat t1_j3iu4of wrote

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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Ornery_Investment131 t1_j3oxddl wrote

That's like asking how does the carburetor know how much air and gas to admit and how to mix them or how a loom knows what threads go where. The carburetor and loom do what they do because that's what that machine does when it's running. Because the physics will be followed, they will not make smoothies and they will not sort coins. Inside the cell are little machines that evolved to do exactly what they do because of chemistry (which is really just physics) and it literally took millions of years and countless generations for them to evolve to this astounding level of complexity. The spindle apparatus is no more intelligent than an engine cam or a loom shuttle but it does what it does when it has the proper inputs, a whole lot of helper machines around it and a source of power.

The actual names of the little machines that guide the spindles are Aurora Kinase A and B and a couple other proteins. They are like jigsaw puzzle pieces that only fit in the specific places that they're supposed to fit.

Watch this video for a general overview of cellular machinery and please excuse the anthropomorphism, it's irresistible when you see some of these little buggers work.

https://www.youtube.com/watch?v=dp6qRNNGPj4

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ihaveredhaironmyhead OP t1_j3pksvo wrote

If I was a creationist (I'm definitely not) this is definitely what I would cite as the strongest evidence of a creator. It truly boggles the mind that random interactions of molecules can lead to something like a cell which is way more than the sum of its parts - and it's driven by the same forces that pull the rock from your hand to the floor. Going into my biology education I thought the cell was just a house to protect fragile DNA. But the cell is really what you are... The DNA contains instructions to build the first cell of your life but after that the DNA is not involved in cellular division. It's just chemistry and ultimately physics. Is that right? It makes me think we have no free will and everything is just what happens when you have a big Bang and let billions of years happen.

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