The word describes a type of cell. The name comes from Greek pro- (meaning before) and karion, meaning nut or kernel. Prokaryotes are cells that do not have a cell nucleus, and lack other things eukaryotes (cells with a true nucleus) have. Prokaryotes do not have membranes inside the cell. This means that there are no vacuoles, Golgi apparatus, endoplasmic reticula or other organelles inside the cell.
Prokaryotes are unicellular. They are either bacteria or archaea. The Archaea include simple organisms, that were first discovered in extreme environments. Most of them can survive at very high or very low temperatures. Some of them can also survive in highly salty, acidic or alkaline water. Some have been found in geysers, black smokers or oil wells.
Cells with a nucleus are called Eukaryotes. Eukaryote cells include organelles which were once free-living prokaryotes. These are like cells but they do not have any organelles, they actually infect in the cells, a virus infects a cell by attaching to it and injecting viral nucleic acid. Eventually the nucleic acid directs the cell to make more viral nucleic acid and protein coats.
- Excluding viruses