What is the maximal possible size of a single cell organism? Why can’t a single cell be the size of a coin for example?
In: Biology
Every cell has the problem of “surface area” vs “energy/water needed” for all the cells inner components to run.
If you make a cell (and it’s insides) too big, it becomes less and less efficient to move water in and out. Imagine a football sized mitochondria with the same energy transfer system as the tiniest one. Instead of requiring a few drops of water in a week, it now needs gallons a day. And the cell doesn’t have an internal storage system for gallons of water. Or plumbing to get it in or out. And then you have issues with things like water evaporating from a giant membrane. Basically every energy & water problem a small cell has, but on such bigger scales cells would need to fundamentally “re-evolve” to address these bigger problems.
The current largest known single cell is an algae that can grow up to a foot long. And, “It independently evolved a form that resembles the organs of land plants. A stolon (a vein like stiff water tube) runs along the surface that the cell is growing on and from the stolon arise leaf-like structures…” So it can grow this large because it lives in water, which solves the evaporating problem, and it HAS started to fundamentally change how it’s structured compared to most other cells.
Most single celled organisms figured out a better way to increase in size is to just clump a bunch of smaller cells together so the same mechanisms can still work for each cell individually.
Latest Answers