The native molecular weight can be estimated by gel filtration using standard proteins of known molecular weight. The subunit molecular weight can be determined by SDS-PAGE using standard proteins of known subunit molecular weight. The native molecular weight is divided by subunit molecular weight and rounded to the nearest whole number. If the native molecular weight is the same as the subunit molecular weight , then the protein is a monomer. Pure proteins must be used in these analyses since a mixture of proteins will give confusing results.
Thoughtful answers get the credit here.
One answer and a potential way to explain exist of mitochondrial DNA and proteins encoded by it, is that these unique organellar proteins encoded by the mitochondrial DNA can not get into the mitochondria due to their unusual properties. In other words, the cellular mechanism for sending proteins into organelles can not cope with some of the proteins needed by mitochondria to function, so these unique proteins must be synthesized in the mitochondrion. Another answer, is that mitochondrial DNA gives the organelle more control over its metabolism and enhances cellular regulation of overall metabolism via coordination of mitochondrial development with total cellular development. Existence of mitochondrial DNA and RNA may allow for communication between the nucleus and the organelles. In other words, since the mother donates the egg which has cytoplasm and therefore, cytosolic DNA, and the father does not since the sperm transfers its DNA to the egg without transferring cytoplasm, this mechanism of transferring DNA to the offspring gives some advantage in the evolution of eukaryotic organisms by having two pools of genetic information being passed on unequally from the two parental types.