14 votes

Mitochondria are alive

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  1. patience_limited
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    From the article: I wasn't aware there was a debate about whether or not mitochondria are "alive" before reading this. My sparsely informed idea was that of course mitochondria aren't just...

    From the article:

    The precise definition of “life” has been debated since the inception of biology as a scientific field. Even today, researchers offer overlapping, but distinct, criteria. Molecular biologists tend to focus on characteristics like metabolism, growth and development, response to stimuli, reproduction, and the ability to process information or evolve. This definition uses “checklists” to determine whether or not an organism is alive.

    Biophysicists often take a more rigorous approach, defining life by means of energetic terms. Physicists Erwin Schrödinger and Ilya Prigogine said that living organisms maintain order despite the universe's tendency towards increasing entropy, a measure of how dispersed or disordered the energy within a system is. Living systems maintain far-from-equilibrium states, constantly exchanging matter and energy with their environment to sustain highly organized structures. Cells take in low-entropy inputs, such as food or sunlight, and expel high-entropy outputs, including waste.

    Regardless of which definition one chooses, mitochondria are clearly alive.

    Mitochondria carry their own genomes and express their own genes within their lumens, an internal pocket of watery space, using biomolecules distinct from the cell’s nucleus. Mitochondria also replicate and divide through binary fission, much like bacteria. If one considers bacteria as living entities — and all biologists seem to — then it is impossible to explain why mitochondria are not.

    I wasn't aware there was a debate about whether or not mitochondria are "alive" before reading this. My sparsely informed idea was that of course mitochondria aren't just hijacked and stripped-down bacterial parts merged into animal cells - I did know they have their own DNA and reproduce independently. But it's kind of cool that we're comprised of cooperating colonies of life that have arrived at something greater than the sum of their parts.

    13 votes