Prokaryotes
The prokaryotes area group of organisms whose cells lack a membrane bound nucleus. They are unicellular organisms, although a few such as myxobacteria have multicellular stages in their life cycles or create large colonies like cyanobacteria. Prokaryotes do not have a membrane bound nucleus, mitochondria,or any other membrane bound organelles. In other words, all their intracellular water soluble components(proteins, DNA, and metabolites) are located together in the same volume enclosed by the cell membrane, rather than in separate cellular compartments. Prokaryotes include 2 major classification domains of life are the bacteria and the archaea were recognized as a domain in 1990. These organism were originally thought to live only in inhospitable conditions such as extremes of temperature,PH and radiation but have since been found in all habitats. Ribosomes in prokaryotes are smaller than in eukaryotes. However two organelles found in many eukaryotic cell. The genome in prokaryote is held within a DNA or protein complex in the cytosol called the nucleoid, which lacks a nuclear envelope. The complex contains a single, cyclic, double stranded molecule of stable chromosomal DNA. Prokaryotes lack mitochondria and chloroplast. Instead, processes such as oxidative phosphorylation and photosynthesis takes place across the prokaryotic cell membrane. However, prokaryotes do possess some internal structures, such as prokaryotic cytoskeletons. They also have a larger surface area to volume ratio giving them a higher growth rate and as a consequence, a shorter generation time than eukaryotes. Most prokaryotes are between 1nanometer and 10nanometer but they can vary in size from zero. They have 4 basic shapes which are cocci-spherical Bacilli-rod shaped spirochaete-spiral shaped vibrio-comma shaped They also live in nearly all