> A simplistic answer is that evolution has made each cell the size best suited to its function.

Yeah. That's probably it. Really, it probably is the right answer.

That just kicks the can forward one step. What parameters control the optimal size of a given cell?

	▲	teravor 2 hours ago \| parent [-]
		there is likely evolutionary pressure against large cell size (selfish genes; larger cell takes energy away from replication, provides more opportunity for infiltration by other genes, fewer gene backups in other cells, etc) while occupying a niche puts pressure to be a certain size. it lands somewhere in the middle.

taneq 2 hours ago | parent | prev [-]

Why are things the way they are? Because it works better. Simple, really. :D