4 ms·

A cell is just literally an organic unit. It’s something organized that is alive. Any living thing would have to have cell’s otherwise it’s just not organized i

A cell is just literally an organic unit. It’s something organized that is alive. Any living thing would have to have cell’s otherwise it’s just not organized in any way which doesn’t make sense in the context of our universe

etskinner 3y ago
This is very close-minded thinking, it's very possible life doesn't require cells
- adrian_b 3y ago
  It is very likely that some kind of life that doesn't require cells must be possible, because it must have existed before the appearance of cells. Cells are much too complex to appear spontaneously, without evolving from an acellular form of life. Cell membranes can form spontaneously from fatty substances, but no cell can live without complex molecular pumps that are embedded in the cell membrane and which bring in some substances from outside and which expel some other substances from inside. Such pumps must be the result of a long evolution that preceded the first cells. Nevertheless, any form of life that is not made of cells cannot live free in a fluid like water, but it must be attached to the surface of some suitable rocks, where a flow of nutrients must exist. The most plausible hypotheses about the appearance of life on Earth suppose that before the appearance of cells, life was restricted to pores inside rocks from hydrothermal vents, where a flow of dihydrogen and of alkaline ions could provide the energy, and metallic sulfide minerals could provide the catalysts for organic syntheses.
- notaustinpowers 3y ago
  The biggest issue is that life has to perform some sort of chemical process. Any lacking any clear delineation of an inside the life in question and the outside, would make continuous chemical processes impossible. A stray breeze blowing away chemicals would effectively kill life. A "cell" having a barrier would allow that chemical process to happen. Life may not require cells in the way cells on Earth evolved, but they'll require cells of some sort.
  - saltcured 3y ago
    I'm trying to imagine some wacky living polymer or protein that wiggles around and grabs whatever molecules it needs to force localized reactions without a protected cell environment. But then I start to wonder if evolutionary pressure would encourage ones that form colonies and eventually closed topologies and cells. And then others might specialize to hijack those colonies...
    - andix 3y ago
      Evolution on another planet can be at any stage. Maybe we are 20 years before those wiggly thingies lose the war ;)
    - rolph 3y ago
      this may help you: https://en.wikipedia.org/wiki/Biomolecular_condensate https://en.wikipedia.org/wiki/Biomolecular_condensate
  - wolverine876 3y ago
    Maybe the planet, or locality on the planet, has resources that permit continuous chemical processes to happen without cell (maybe no breeze). Maybe it doesn't need to be continuous.
- 0xBA5ED 3y ago
  Or... Life requires a closed system which requires a boundary. The boundary and its contents is considered a cell?
  - IggleSniggle 3y ago
    TIL the Earth is a single cell
    - 0xBA5ED 3y ago
      Not from me, since I didn't claim that all closed systems are cells.
- polishdude20 3y ago
  I mean, define "life" then.
  - derekp7 3y ago
    I think that no matter what definition one comes up with, it is possible to have counter examples (i.e., is fire alive, seeing as how it reproduces, consumes food (fuel), etc). One of the indicators of life I like to use, that seems to be useful in the general sense is that life is good at decreasing (fighting against) entropy at a local level. So fire for example increases entropy. A living being takes in raw materials plus energy, and produces a lower entropy (higher organization) of those inputs. Like plants making sugar, and pulling apart CO2 to make free oxygen. Or animals taking in sugar and oxygen, the output is higher entropy (CO2) but you have higher organization of material (lower entropy) locally within that organism. This also means that life doesn't necessarily need to reproduce (although that is how life that we know of works). You could theoretically have a living being that kept evolving its own form but never developed the ability to copy itself. It just keeps consuming energy and environmental items, and maintaining its own internal complex structures.
    - arrosenberg 3y ago
      Fire is not alive, it cannot maintain homeostasis for any period of time. Your bit about entropy is actually looking for the concept of homeostasis.
      - asdff 3y ago
        Fire can maintain homeostasis if it is fed and is able to respire, same as us humans. Take away food and air and we flame out too.
        arrosenberg 3y ago
        No, it actually can't. Fire will burn as hot and quickly as it has fuel and oxygen to sustain, because it's a chemical reaction, it doesn't maintain any kind of steady-state in order to extend it's survival. If you take away my food, I will still have energy to find more. If you take away my air, I will still have air (albeit quite time-limited) to find more. That gradient is how we understand something to be alive.
- timacles 3y ago
  Its very easy to say something like that, but impossible to provide any sort of examples, even in a fantasy context. Like what a gas cloud with intelligence? We live in a universe with distinct rules, saying life doesnt have to have cells is basically fantasizing about other dimensions where we're made out of hot dogs or something. Saying life doesn't require cells is just redefining what words mean, since a cell literally means the smallest functional unit of life.
  - shkkmo 3y ago
    > We live in a universe with distinct rules, saying life doesnt have to have cells is basically fantasizing about other dimensions where we're made out of hot dogs or something. That comparison is ridiculous. We live in a universe for which many of the rules are unclear and we have only grasped some small subset of the possibility space dor emergent structures those rules enable. We have a hard enough time coming up with a clear definition of which of the emergent structures that we do know about qualify as "life". You seem to accept it as settled that viruses are not alive and are mere chemistry but it seems to me like drawing a line in the sand between two similar processes. When we're talking about cells, that seems like an easier thing to define, but I would posit that is another definition that could prove to be slippery if an alien biology without a common ancestor is discovered. We have to be careful about how we define life and cells in relation to each other to avoid just creating tautologies rather than useful definitions. For example, how sure can we be that by defining life to exclude viruses, we haven't defined life in such a way that we have excluded processes that can support consciousness? I think it is pretty easy to imagine life which has "cells" that we fail to recognize as such because they serve a similar function but with a sufficiently different form that we would fail to see or recognize them in a microscope. Now, many of those imaginings may be scientifically impossible but that doesn't justify comparing all of them to "a dimension where we are made of hotdogs."

etskinner 3y ago

This is very close-minded thinking, it's very possible life doesn't require cells

adrian_b 3y ago
It is very likely that some kind of life that doesn't require cells must be possible, because it must have existed before the appearance of cells. Cells are much too complex to appear spontaneously, without evolving from an acellular form of life. Cell membranes can form spontaneously from fatty substances, but no cell can live without complex molecular pumps that are embedded in the cell membrane and which bring in some substances from outside and which expel some other substances from inside. Such pumps must be the result of a long evolution that preceded the first cells. Nevertheless, any form of life that is not made of cells cannot live free in a fluid like water, but it must be attached to the surface of some suitable rocks, where a flow of nutrients must exist. The most plausible hypotheses about the appearance of life on Earth suppose that before the appearance of cells, life was restricted to pores inside rocks from hydrothermal vents, where a flow of dihydrogen and of alkaline ions could provide the energy, and metallic sulfide minerals could provide the catalysts for organic syntheses.
notaustinpowers 3y ago
The biggest issue is that life has to perform some sort of chemical process. Any lacking any clear delineation of an inside the life in question and the outside, would make continuous chemical processes impossible. A stray breeze blowing away chemicals would effectively kill life. A "cell" having a barrier would allow that chemical process to happen. Life may not require cells in the way cells on Earth evolved, but they'll require cells of some sort.
- saltcured 3y ago
  I'm trying to imagine some wacky living polymer or protein that wiggles around and grabs whatever molecules it needs to force localized reactions without a protected cell environment. But then I start to wonder if evolutionary pressure would encourage ones that form colonies and eventually closed topologies and cells. And then others might specialize to hijack those colonies...
  - andix 3y ago
    Evolution on another planet can be at any stage. Maybe we are 20 years before those wiggly thingies lose the war ;)
  - rolph 3y ago
    this may help you: https://en.wikipedia.org/wiki/Biomolecular_condensate https://en.wikipedia.org/wiki/Biomolecular_condensate
- wolverine876 3y ago
  Maybe the planet, or locality on the planet, has resources that permit continuous chemical processes to happen without cell (maybe no breeze). Maybe it doesn't need to be continuous.
0xBA5ED 3y ago
Or... Life requires a closed system which requires a boundary. The boundary and its contents is considered a cell?
- IggleSniggle 3y ago
  TIL the Earth is a single cell
  - 0xBA5ED 3y ago
    Not from me, since I didn't claim that all closed systems are cells.
polishdude20 3y ago
I mean, define "life" then.
- derekp7 3y ago
  I think that no matter what definition one comes up with, it is possible to have counter examples (i.e., is fire alive, seeing as how it reproduces, consumes food (fuel), etc). One of the indicators of life I like to use, that seems to be useful in the general sense is that life is good at decreasing (fighting against) entropy at a local level. So fire for example increases entropy. A living being takes in raw materials plus energy, and produces a lower entropy (higher organization) of those inputs. Like plants making sugar, and pulling apart CO2 to make free oxygen. Or animals taking in sugar and oxygen, the output is higher entropy (CO2) but you have higher organization of material (lower entropy) locally within that organism. This also means that life doesn't necessarily need to reproduce (although that is how life that we know of works). You could theoretically have a living being that kept evolving its own form but never developed the ability to copy itself. It just keeps consuming energy and environmental items, and maintaining its own internal complex structures.
  - arrosenberg 3y ago
    Fire is not alive, it cannot maintain homeostasis for any period of time. Your bit about entropy is actually looking for the concept of homeostasis.
    - asdff 3y ago
      Fire can maintain homeostasis if it is fed and is able to respire, same as us humans. Take away food and air and we flame out too.
      - arrosenberg 3y ago
        No, it actually can't. Fire will burn as hot and quickly as it has fuel and oxygen to sustain, because it's a chemical reaction, it doesn't maintain any kind of steady-state in order to extend it's survival. If you take away my food, I will still have energy to find more. If you take away my air, I will still have air (albeit quite time-limited) to find more. That gradient is how we understand something to be alive.
timacles 3y ago
Its very easy to say something like that, but impossible to provide any sort of examples, even in a fantasy context. Like what a gas cloud with intelligence? We live in a universe with distinct rules, saying life doesnt have to have cells is basically fantasizing about other dimensions where we're made out of hot dogs or something. Saying life doesn't require cells is just redefining what words mean, since a cell literally means the smallest functional unit of life.
- shkkmo 3y ago
  > We live in a universe with distinct rules, saying life doesnt have to have cells is basically fantasizing about other dimensions where we're made out of hot dogs or something. That comparison is ridiculous. We live in a universe for which many of the rules are unclear and we have only grasped some small subset of the possibility space dor emergent structures those rules enable. We have a hard enough time coming up with a clear definition of which of the emergent structures that we do know about qualify as "life". You seem to accept it as settled that viruses are not alive and are mere chemistry but it seems to me like drawing a line in the sand between two similar processes. When we're talking about cells, that seems like an easier thing to define, but I would posit that is another definition that could prove to be slippery if an alien biology without a common ancestor is discovered. We have to be careful about how we define life and cells in relation to each other to avoid just creating tautologies rather than useful definitions. For example, how sure can we be that by defining life to exclude viruses, we haven't defined life in such a way that we have excluded processes that can support consciousness? I think it is pretty easy to imagine life which has "cells" that we fail to recognize as such because they serve a similar function but with a sufficiently different form that we would fail to see or recognize them in a microscope. Now, many of those imaginings may be scientifically impossible but that doesn't justify comparing all of them to "a dimension where we are made of hotdogs."