6 - Fungal Mitochondrial Genomes, Plasmids and Introns

摘要: Within the fungi mitochondrial genomes can exist as either linear or circular molecules, whose size variation is mostly due to presence absence of optional introns, and in intergenic regions. Optional introns be group I II which are potential ribozymes that, part, catalyze their own removal from precursor RNA transcript. Mitochondria also contain autonomously replicating DNA that derived represent true plasmids show no homology with chromosome. True cryptic nature, may have a different evolutionary origin host-genome. Amongst at least three categories recognized: (1) Circular encoding polymerase; (2) terminal inverted repeats an polymerase and; (3) retroplasmids, encode reverse transcriptase. These groups probably arose independently one another, were vertically transmitted original endosymbiont gave rise mitochondrion, invaded mitochondrion various times during fungal evolution.