nucDNA vs mtDNA

Alternative Vertebrate Genomes: nuclear & mitochondrial DNA

    The nucDNA genome in typical vertebrates consists of several billion base pairs of DNA, arranged on paired chromosomes, one inherited from each parent. The human genome shown here comprises 3 billion bp in 22 pairs of autosomal chromosomes and one pair of sex chromosomes, XY in this (male) individual.

    The mtDNA genome is a much smaller, circular molecule about 16 ~ 18,000 bp in circumferance in most vertebrate species. The genome comprises 13 protein-coding regions, two rRNA genes, a replication control region, and 22 tRNA genes. The order of these is broadly conserved across vertebrates. There are no introns: splicing out of tRNAs produces mRNA templates. The mtDNA genome is self-replicating with the aid of nucDNA-encoded polymerases. The genome is locted is the extranuclear mitochondria, the "powerhouses of the cell," where it contributes to cell respiratory systems in the Cytochrome Oxidase, ATP synthase, and NADH systems. The vertebrate mtDNA genetic code differs from the "Universal" code is several respects.

    Unlike the nucDNA genome, the mtDNA genome is inherited solely through the cytoplasm of the maternal egg, and does not undergo genetic recombination. It has therefore been widely used in evolutionary and population biology to trace maternal lineages within and between species.

FISH chromosomes © Applied Imaging, UK; all text material © 2005 by Steven M. Carr