Variations in Mitochondrial Genome Size

The size and number of genes in mitochondrial genomes vary widely among different organisms.

• Human mitochondrial genomes are relatively small, at around 16 kb.
• Yeast mitochondrial genomes are around 80 kb.
• Plant mitochondrial genomes are around 200 kb.
• The largest sequenced mitochondrial genome is that of the plant Arabidopsis thaliana, at 367 kb.
• The protozoan Recclinomonas americana has the greatest number of genes in its mitochondrial genome, with 97 genes in a genome of only 69 kb.

These variations in size and number of genes are thought to be due to a number of factors, including the different metabolic requirements of different organisms, the history of gene duplication and deletion, and the rate of mutation.