Vertebrate mitochondrial DNA (mtDNA)
The mtDNA genome is a small, circular
molecule, about 16 ~ 18,000 base pairs in circumference in most
The genome comprises 13 protein-coding regions,
rRNA genes, a replication control
and 22 tRNA genes. The order of
is broadly conserved across vertebrates. There are no introns: splicing
out of tRNAs produces mRNA templates, and the terminal "A" of some stop codons is produced
as part of poly-adenylation.
is self-replicating with the aid of nucDNA-encoded
polymerases. It contributes
to cell respiratory systems in the Cytochrome Oxidase, ATP
and NADH systems. The vertebrate mtDNA
genetic code differs from the "Universal" code is several respects.
inherited solely through the maternal egg cytoplasm, the paternal sperm
mitochondria making no contribution. This, plus the absence of genetic
recombination, allows the mtDNA molecule
to be passed on intact from mother to daughter. It has therefore found
great application in evolutionary
and population biology as a molecular marker.