What benefits does compartmentalisation confer on cells?

Intro: Look at caveats in the question:Not all cells are compartmentalised - e.g. prokaryotic cellsThis therefore tells us that compartmentalisation is likely an adaption to a set of biological niches.(If compartmentalisation was purely beneficial, we would not expect non-compartmentalised cells)Eukaryotic cells are therefore likely to have compartmentalisation as it offers some selective advantages in certain environments.Firstly: Define a cellular compartment: - a lipid-bilayer that generates two distinct cellular environmentsWhat important physical properties: Semi permeable - water is able to diffuse through (NB: aquaporins), but ions are unable to freely move across membranes. We see these membranes as defining cellular organelles. These properties define our benefits. (always link back to chemistry if possible)Secondly: BenefitsFundamentally different ionic concentrations in different organelles. - an organelle's interior can be different to its exterior.This allows: 1) concentration gradients to form which can be used to generate energye.g. ATP synthase and H+ gradientConcentration gradients can be coupled to the transport of ions against their concentration gradient 2) safety in substrate degradation can enclose degradation in a highly acidic organelle whose enzymes can only function in highly acidic conditions (and if released would not damage the cell). 3) organelle specialisationOrganelles can have unique subsets of enzymes that allow confined cellular processes to occur.This can speed up reaction kineticsAlso potentially competing enzymes do not inhibit each other.e.g. degradative processes vs anabolic processes. 4) energy storage the ability to have ionic gradients means that not reliant on the extracellular environment to provide energy.Compartmentalisation also allows protection of an organelles contents and directionality of processes.e.g. during Protein synthesis, DNA is protected in nucleus by the nuclear membrane.e.g. during secretion, proteins are transferred sequentially through membranous compartments (e.g. ER, Golgi stacks). This allows sequential modification (e.g. glycosylation).Membranes provide locations for specialised processes.e.g. Organelle contacts provide specific cues for processes: e.g. endosomal tubule fissione.g. Export from an organelle can allow error-checking steps: e.g. nuclear export, or import into the ER requiring a Signal Sequence. means that the correct proteins can be processed appropriately to allow accurate distribution.Etc.