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Thread: Cells??

  1. #1 Cells?? 
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    What's the difference between living and dead cells?

    Can you duplicate the arrangement of atoms to create a living cell? How do you duplicate the information and the deciphering system?


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  3. #2  
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    'What's the difference between living and dead cells?

    Can you duplicate the arrangement of atoms to create a living cell? How do you duplicate the information and the deciphering system?'

    Dear J,
    Living cells carry out energy-harvesting metabolic processes which ultimately serve to provide the energy necessary for the cell to maintain order (to replicate its DNA correctly etc) and to divide (assuming the cell is not quiescent).

    Living cells sometimes 'choose' to die, or undergo Apoptosis (for example, in response to receipt of irreparable DNA damage). There are two main pathways of Apoptosis: the Extrinsic and the Intrinsic pathway. The Extrinsic pathway is triggered, for example, upon binding of extracellular death ligands to their corresponding homotrimeric death receptors on the target cell. In contrast, the Intrinsic pathway is typically induced in response to internal stress signals (including DNA damage). In this specific case, p53 serves to up-regulate the pro-apoptotic BH123 protein Bax, which when activated, inserts into the outer mitochondrial membrane (OMM), where it mediates mitochondrial membrane permeabilisation (MOMP). Cytochrome C is released from the intermembrane space of the mitochondrion and helps to form the Apoptosome which in turn activates initiator procaspases into caspases. This caspase cascade is irreversible.

    The point is: whilst the exact point at which a cell is said to be 'dead' rather than 'alive' is to some extent arbitrary (because cell death is a process as opposed to a stochastic event), the induction of MOMP is considered THE critical event in commitment to mitcohondrial Apoptosis by many leaders in the cell death field. (Because it ushers in an essentially irreversible 'caspase cascade' and therefore represents a 'point of no return' for the dying cell).

    I'm sorry, I don't understand your last two questions.

    Hope this helps!

    Best wishes,

    Tridimity :-D


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  4. #3  
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    Oops I forgot to mention, the Bcl-2 protein family is largely responsible for regulating Bax activation!

    :wink:
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  5. #4  
    Forum Radioactive Isotope skeptic's Avatar
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    Craig Venter, who was one of the pioneers who decoded the human genome, is working on creating artificial life. This will take the form of a very simplified bacterial-like organism, probably incapable of living away from the artifical environment and nutrients that the lab will supply.

    http://blogs.discovermagazine.com/80...-craig-venter/

    This is not quite like creating a cell, but it is a beginning. Venter certainly believes that synthetic life, in the form of cells, is possible. He expects to create such eventually. Do not hold your breath though. It will take many years.
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  6. #5  
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    The initial question simply asked what were the definable characteristics that separated a living cell (the basic unit of life) from a dead one, without the need, or much less the desire to go into the molecular procedural details involving cellular apoptosis.

    These definable characteristics are ubiquitous in all organisms, from unicellular (archaea and bacteria) to multicellular (animals, plants, and fungi) organisms, all share properties that are common to living things, as opposed to inorganic or inanimate objects. All are of carbon and water based form, with complex organisation and heritable genetic information. They all undergo metabolism, maintain homeostasis, and possess the ability to grow, respond to stimuli, reproduce, and evolve in response to their environment. Any organism or object that does not fulfil the totality of these self-sustaining biological processes can therefore not be considered as possessing life, or of having a biological function.

    In relation to the genetic information idea, synthetic biologists fiddle around with genetic sequences to engineer desired traits or phenotypes. But as things stand, genetic sequencing and engineering exist primarily to provide information on naturally occurring organisms. Parts and devises may be manufactured and engineered to build novel biological functions and systems but are not fabricated on an atom-to atom basis but derived from pre-existing parts, or systems…..additionally, I see absolutely no utility in duplicating the arrangement of atoms to produce a living organism.
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