MALDI-TOFTOF

How come IgG isotypes are used as secondary antibody for detection when performing a serum-ELISA and not IgM? It says so in a course immunology, but I can not find the underlying reason.

First of all you have to realise that mitochondria and other organelles in fact originated from endocytoses of bacteria in other cells early in evolution. This is in fact the origin of eukaryote cells. These bacteria had their own dna ofcourse, but have lost a lot of it during evolution, nut not everything. Thus they remain with some imortant genes for the organelle function. Second, what you think as: one species, one dna reflects on nuclear dna. But even then it's not entirely correct. Within a species the gene content is alike, but a lot of differences exist within the genes. Thirdly, when you look at conception, you see that the spermatozoïd is very small, and carries only dna, from the father. But after conception, there is a need for proteïns to start cell division. That is why the egg cel is much bigger, because next to its nuclear dna it contains cytoplasm with the Endoplasmic reticulum, ribosomes, etc. But also mitochondria, so the dna of the mitochondria is passed through the egg cell, or in other words: by the mother