Organelle genomes
DNA maps for mitochondria and chloroplasts. Many of the organelle genes encode proteins that carry out the energy-producing functions of these organelles (green), whereas others (red and orange) function in protein synthesis. (a) Maps of yeast and human mtDNAs. (Note that the human map is not drawn at the same scale as the yeast map.) (b) The 121-kb chloroplast genome of the liverwort Marchantía polymorpha. Genes shown inside the map are transcribed clockwise, and those outside are transcribed counterclockwise. IRA and IRB indicate inverted repeats. The upper drawing in the center of the map depicts a male Marchantia plant; the lower drawing depicts a female.
[Data from K. Umesono and H. Ozeki, Trends Genet. 3, 1987.]