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Thread: tubulin - microtubles - army ants

  1. #1 tubulin - microtubles - army ants 
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    Reading about mitosis, I was impressed with the part microtubules play in this process.
    They are made from the protein tubulin.
    http://en.wikipedia.org/wiki/Tubulin

    The alpha-beta construction of tubulin provides polarity enabling a chain-like extension.
    It also connects sideways to other strings to form a tube.

    Some microtubules extend to reach specified spots on chromosomes (kinetechore proteins).
    They attach to different chromosomes, depending on the phase of mitosis or meiosis.
    They exert appropriate pulling force (shortening themselves) until the chromosomes are at a certain point.
    http://en.wikipedia.org/wiki/Kinetochore

    Other microtubules extend but don't touch the chromosomes; they slip past them to exert guidance and pushing forces.

    But the action of tubulin protein building itself into microtubules reminded me of certain army ants that form living bridges
    with their bodies.
    http://www.alexanderwild.com/Ants/Ma...70631814_E9ee5
    http://www.youtube.com/watch?v=6q0MxT_ULH0

    Something (instinct?) enables the ants to do their thing.

    Does anybody know how proteins like tubulin do their thing?


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  3. #2  
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    Hey,

    I just composed a very detailed answer and then it timed-out so i lost the entire thread. Therefore please excuse my brevity, but they basically do it through the property of dynamic instability and with the help of Microtubule Associated Proteins (MAPs), one subset of which, the +TIPs, tend to promote the formation of long, probing MTs.

    Here are some links:

    http://en.wikipedia.org/wiki/Dynamic...ic_instability

    http://en.wikipedia.org/wiki/Microtu...ciated_protein

    I've also found a fairly good Nature Reviews article on MAPs, I have access through my University account so if you are interested in reading it just let me know and I will e-mail it to you.

    Thanks,

    Tri 8)


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  4. #3  
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    Quote Originally Posted by tridimity
    they basically do it through the property of dynamic instability
    Thanks for your info.

    The word "instability" has a negative connotation.
    Why is it used to describe the operation of microtubules that evidently do many things at the right time?

    If I had a staff doing a number of things successfully, I wouldn't call them unstable.

    Would you be able to explain this property as it relates to microtubules?
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  5. #4  
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    the property of dynamic instability means that in laboratory conditions the microtubules are prone to spontaneously disasemble(as a result of being unstable), because a protein complex that keeps them stable will degrade at the top. this process is not a problem when you constantly add more protein complex to the top(making the tube longer). however when you stop, the protein complex will degrade and the whole thing will fall appart very rapidly.

    contrary to the "negative connotation" that instability has, in many cases you may want a reaction to go quickly, in such cases you're best off if the reactants are unstable. when you want microtubules that can quickly retract when not extending, dynamic instability is a useful property.
    physics: accurate, objective, boring
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  6. #5  
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    Quote Originally Posted by saul
    the property of dynamic instability means that in laboratory conditions the microtubules are prone to spontaneously disasemble(as a result of being unstable),
    Does that mean it only refers to laboratory conditions?

    This page "Microtubule Structure" says:
    "Thus, they are in a continued state of flux. This is believed to respond to the needs of the cell and is called "dynamic
    instability".
    http://www.cytochemistry.net/cell-bi..._structure.htm

    Say a football player has the ability to play a number of positions effectively.
    The coach assigns him to do this during the game.
    The player is in a continued state of flux (def. a continuous moving on or passing by).
    This is done to respond to the needs of the team.
    When the headlines say: "Football player is unstable!", what do most people think?

    Seems to me they could have selected a better phrase to associate with the jobs done by the efforts of tubulin, MAPs, etc..

    Specific question:
    Is it known how the microtubules exert a pulling force, to pull the chromosomes?
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