Gene transcription occurs in both eukaryotic and prokaryotic cells. Membranes serve diverse functions in eukaryotic and prokaryotic cells. Chytrids mainly infect algae and other eukaryotic and prokaryotic microbes. The structures of both eukaryotic and prokaryotic genes involve several nested sequence elements. Mitochondria are essential organelles in eukaryotic cells. Many types of prokaryotic and eukaryotic cells have a cell wall. It is toxic to prokaryotic and eukaryotic cells. Mixotrophs can be either eukaryotic or prokaryotic. Below are tables of common prokaryotic and eukaryotic endonucleases. There are two types of cells, eukaryotic and prokaryotic. The photobionts in lichens come from a variety of simple prokaryotic and eukaryotic organisms. Inverted repeats are often described as "hotspots" of eukaryotic and prokaryotic genomic instability. Comparative genomic studies allow for comparison of eukaryotic genomes. It is implemented both in eukaryotic and prokaryotic systems. The nucleus is an organelle found in eukaryotic cells.