prokaryoottisolut

Prokaryoottisolut, or prokaryotic cells, are cells that lack a membrane-bound nucleus and other membrane-bound organelles. They form the two biological domains Bacteria and Archaea and are among the earliest forms of life. Their genetic material is typically a single circular chromosome located in a region called the nucleoid, and many species also carry smaller circular DNA molecules called plasmids. Prokaryotic cells generally have a cell envelope consisting of a cell membrane and, in many species, a rigid cell wall. Bacterial cell walls often contain peptidoglycan, while archaeal walls may be composed of other polymers such as pseudopeptidoglycan. Some prokaryotes also have an outer membrane, or a capsule, and numerous surface appendages such as flagella or fimbriae.

Biochemical and genetic capabilities of prokaryotes are diverse. They reproduce asexually by binary fission, enabling rapid population growth. In addition to vertical inheritance, they exchange genetic material through horizontal gene transfer mechanisms such as transformation, transduction, and conjugation, which contribute to genetic diversity. Metabolic strategies are varied: many are photoautotrophs or chemoautotrophs, while others are heterotrophs. This metabolic versatility allows prokaryotes to inhabit virtually every environment on Earth, from soil and water to extreme places like hot springs and acidic environments.

Ecologically, prokaryotes play essential roles in nutrient cycling, decomposition, and symbiotic relationships. Some are harmless or beneficial, while others are pathogenic to humans, animals, or plants. Antibiotics target bacterial features such as cell wall synthesis or bacterial ribosomes, underscoring the medical relevance of prokaryotes. Compared with eukaryotic cells, prokaryotes are generally smaller, lack a nucleus and mitochondria, and possess 70S ribosomes.