Why are cells small? Why do they need to reprimary small in size? originally appeared on Quora: the expertise sharing network wbelow compelling questions are answered by civilization via unique insights.

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Answer by Dave Featherrock, Professor of Biology/Neuroscience, on Quora:

Textbooks and also the majority of instructors will tell you that cells have to be tiny bereason they need a high ‘surface to volume’ proportion, which is good for exchanging products in between the inside and also outside of cells. But this is more than likely not really the size-limiting reason, given that cells differ enormously in dimension and surchallenge location to volume ratios. Bacteria are tiny compared to animal cells, for instance. And plant cells surround themselves through a cell wall that considerably boundaries exadjust via the extracellular civilization. If exadjust were limiting, then pet cells would certainly be as tiny as bacterial cells. Or pet cells without cell walls might be a lot bigger than plant cells. Or plant cells through cell walls would be a lot smaller sized.


Others could tell you that cell size is limited by diffusion rates. You can’t have actually an extremely massive cell bereason it would take also lengthy for things to float from one side of a cell to the other. But this mirrors a deep misknowledge of just how crowded the insides of cells are. Nopoint simply ‘floats’ about from one side of the cell to the various other. Almost nopoint in cells is diffusion limited. Most points are transported around in cells. Also, cells can be extremely, extremely long. Neurons can be numerous feet lengthy. So obviously cells are capable of handling huge ranges.

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I think cells are little bereason membranes are weak. If the cell gets too significant, the cell will fall acomponent. I think this explains why bacterial cells are tiny — they don’t have much cytoskeltal ‘reinforcement’ (although they do have cell walls), and also why substantial cells deserve to acquire incredibly big. Muscle cells and neurons have a lot of reasonably hard cytoskeleton in them. This helps organize them together, and also therefore they have the right to be quite big. Egg cells (choose chicken eggs) have actually a difficult shell. And they are extremely huge. What happens if you crack an egg shell?

At some point, I don’t recognize why cells are little. But you should notice that I did notthoughtlessly accept what textpublications or my teachers told me. I thought around it closely, and came up through my own idea that fits as a lot evidence as I deserve to think of. The following action for a scientist would certainly be to test my idea. Perhaps I can meacertain cell membrane toughness for a many various cells and compare it to cell size? My hypothesis predicts that cell dimension and also membrane strength would certainly be extremely correlated. Maybe I deserve to threaten cell membranes in some organism and view if it adapts by evolving smaller sized cells?


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