árchaea

Archaea are a domain of single-celled microorganisms. These organisms are prokaryotic, meaning they lack a membrane-bound nucleus and other organelles. Like bacteria, archaea are typically a few micrometers in length and possess a cell wall, though their cell wall composition differs significantly from bacteria. Archaea can be found in a wide variety of environments, including extreme conditions such as hot springs, salt lakes, and deep-sea hydrothermal vents. Some archaea are extremophiles, meaning they thrive in environments that are hostile to most other life forms.

Historically, archaea were classified as bacteria, but they are now recognized as a distinct domain of life. Genetic and biochemical studies have revealed that archaea share some characteristics with both bacteria and eukaryotes, but they are more closely related to eukaryotes than to bacteria. For example, archaea have unique RNA polymerase enzymes and ribosomes that are more similar to those of eukaryotes. Their genetic material is also organized differently from bacteria.

Archaea play important roles in various ecosystems. Some archaea are involved in nutrient cycling, such as the nitrogen cycle, while others are found in the digestive tracts of animals, including humans. Methanogens, a group of archaea, produce methane gas as a metabolic byproduct, which has implications for the global carbon cycle and climate change. Other archaea are chemosynthetic, obtaining energy from chemical reactions rather than sunlight. The study of archaea continues to reveal new insights into the diversity of life on Earth and its evolutionary history.