The mitochondria are constantly translocated along microtubule chains to locations in the cytoplasm where nutrients (triglyceride droplets, puryvate) are available. How the mitochondrion is directed is not known. A hypothesis is that it is transported by fluid movements to locations with a higher osmotic pressure. When a mitochondrion has absorbed puryvate and phosphate ions, the local osmotic pressure in the cytosol around the mitochondrion is decreased. This is assumed to cause a movement of water carrying the mitochondrion (and lipid droplets) to a neighboring location, with higher concentration of puryvate and phosphate ions, thus with a higher osmotic pressure; the exchanges ADP-ATP and 02-CO2 do not change the osmotic pressure.
In young cells the mitochondrion is assumed to travel rather easily along a protein chain. However, in old cells the path to the nourishment is assumed to be obstructed by cross-linkages, leading to a decrease with age in function.