The Exon: Intron Structure of Some Mitochondrial Genes and Its Relation to Mitochondrial Evolution

Publisher Summary This chapter discusses the exon–intron structures of some mitochondrial genes, examines the mitochondrial intervening sequences, and surveys their characteristic properties. Mitochondrial DNA is a physically and biochemically discrete entity, which is distinct and readily separable from its classical nuclear counterpart. Large mitochondrial genomes that are more representative of ancestral forms than are the more streamlined versions found in animals exhibit architecture both within and among their genes that are analogous to those found in large nuclear genomes. A number of similarities and additional features of mitochondrial genes and their expressions (such as codons, tRNAs, codon utilization, transcription, and processing of transcripts), which diverge from their prokaryotic counterparts, show that a mitochondrial ancestor is unlikely to have borne any resemblance to a contemporary Eubacterium.