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Atomic/Physic description of life, growth and evolution

  1. Dec 1, 2011 #1
    I have no idea where this topic belongs since it combines physics and biology.

    Is there a way to describe life, growth, and evolution in terms of Atoms or Physics. Or are they two completely different things?
     
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  3. Dec 1, 2011 #2

    Ryan_m_b

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    The laws of physics govern everything; chemistry and by extension biology are emergent properties of those laws. You're question is quite vague, can you give examples of what you're trying to find out?
     
  4. Dec 1, 2011 #3
    Actually, the main thing that I m looking for is how (in an Physic's sense) do cells of living organism replicate themselves.
     
  5. Dec 1, 2011 #4

    Ryan_m_b

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    I'm still not sure what you mean by "in a physics sense"? Fundamentally organisms are the product of biochemistry, these chemical reactions occur due to the laws of physics. Cells of eukaryotic organisms replicate via mitosis and cytokinesis, prokaryotes replicate via binary fission.
     
  6. Dec 1, 2011 #5

    Pythagorean

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    Well, first, organisms replicate their "code" or DNA; they don't do it perfectly, of course, but neither does a production plant perfectly produce the same design). However, in both cases, the result is generally functionally equivalent. When these copy errors are not functionally equivalent, we call it a mutation or evolution.

    Go here, under DNA, click Replication. It will show you what the molecules are doing during replication. All the constituents are available, floating around in the region of the cell; the information about the form and structure is what transfers from a structured set of molecules to a bunch of free-floating molecules through electrodynamic interactions (reactions, attraction, repulsion) and concentration gradients. Some molecules can come together and form a little machine that handles specially designed reactions that help the process of replication, but they still operate on these principles.

    At the physics level, you could see this as a bunch of electrodynamic interactions, but the reactions would require some quantum physics to understand. Chemists generally learn this as "physical chemistry".

    Cellular replication requires the previously mentioned molecular machines. Now that there's a new copy of the code, a new cell can be made, using that copy. You can look at mitosis or meiosis in that website to see what's going on with the actual molecules. Basically, another nucleus is built inside the membrane and the membrane seals and separates into two membranes, each with their own nucleus (which each has their own copy of the code).

    From there, the new replicated code is "interpreted" by molecular machines and cells turn into specific kinds of cells and form bonds with their neighboring cells, and keep making new cells. In development of new offspring, this is called morphogenesis and really comes back to molecular machines (and structures) following "directions" from the code. They are really always just following the laws of classical and quantum electrodynamics and diffusion and gravity, but....

    It is a very complex arrangement of events that can happen following these simple rules (because of the complicated geometry of all the different particles.. especially carbon). So we call different events that we see a lot by a specific names like DNA, cell, proteins (which can be both "molecular machines" and "signals"; terms we associate with our ever day life, but aren't quite the same. It's just a way to try and archive all the complicated interactions underlying life so that we can make sense of them).
     
    Last edited: Dec 1, 2011
  7. Dec 1, 2011 #6
    From your descriptions the word, 'molecular machine', 'protein' sound like a black boxes where we have no idea what is happening inside but we know that they do something to make cellular replication possible.

    I would like to know what that 'complex arrangement of events' are and how they are achieved.

    I'm grateful that they are archived under comprehensible terms. But they do (in my opinion) hide or cover up how exactly they work.
     
  8. Dec 1, 2011 #7

    atyy

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  9. Dec 2, 2011 #8

    epenguin

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    Is this http://en.wikipedia.org/wiki/DNA_polymerase an example of a black box?

    You seem to be asking 'explain to me basic molecular and cellular biology' .

    We are running a satire on this sort of question on another thread. :tongue:
     
  10. Dec 2, 2011 #9

    Pythagorean

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    They are generalist terms, so they are not specific. The particular proteins are vast and diverse.
     
  11. Dec 2, 2011 #10

    Ryan_m_b

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    No we have a pretty good idea what's happening. When we use the term "molecular machine" we are trying to describe the ensemble of molecules that work together to perform a function. A protein is a polymeric molecule made from amino acids. Did you look at the link Pythagorean provided above? It was very good as was his explanation.

    Here are a few videos on DNA replication you might like to watch

    https://www.youtube.com/watch?v=gL3aigv7w4A
    https://www.youtube.com/watch?v=-mtLXpgjHL0
    https://www.youtube.com/watch?v=qn-JW-M89fo&

    What you are seeing are computer visualisations of a DNA replication fork. Each individual molecule is acting simply due to their, and their environment's, chemical properties. DNA is made out of two chains of nucleotides, there are four types; A, C, G, T. The two chains of DNA bind together in a helix, this binding occurs because T binds to A and C binds to G. When new DNA is being synthesised new nucleotides are added by DNA polymerase. These nucleotides are found floating around (though in their free form they have pyrophosphate bound) and when they come in contact with DNA polymerase a energetically favourable chemical reaction occurs leading to the removal of the pyrophosphate and binds the nucleotide to the growing chain.
     
  12. Dec 16, 2011 #11
    Your question is vague, as already stated. Moreover, you are posing a false dichotomy. The question to ask is, Can everything in biology be explained in terms of physical laws and entities, e.g. atoms?

    Answer: read Ernst Mayr, the best writer and thinker in the field.
     
  13. Dec 16, 2011 #12
    Thanks so much for that link. I'd never heard of Mayr before. As somebody who has moved back and forth between philosophy and the sciences, I often crave this sort of thing.
     
  14. Dec 17, 2011 #13
    You're welcome. Mayr is one those guys of whom one says, If Mayr wrote it, it's worth reading it. Whether or not you agree with him, he was such an awesome writer and such a great biologist. The man worked at Harvard until his death - at 100 years of age!
     
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