Three-domain system
... The three-domain system is a biological classification introduced by Carl Woese in 1977[1][2] that divides cellular life forms into archaea, bacteria, and eukaryote domains. In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria (now Bacteria) and Ar ...
... The three-domain system is a biological classification introduced by Carl Woese in 1977[1][2] that divides cellular life forms into archaea, bacteria, and eukaryote domains. In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria (now Bacteria) and Ar ...
the evolution of the cell
... separate from the DNA found in the nucleus of the cell. And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles ...
... separate from the DNA found in the nucleus of the cell. And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles ...
Board Bulletin Offical Notice
... one of the following and identify the role of this organism in its ecosystem: - Archaea - Eubacteria - Cyanobacteria, including those that form stromatolites - nitrogen fixing bacteria - methanogens - deep-sea bacteria ...
... one of the following and identify the role of this organism in its ecosystem: - Archaea - Eubacteria - Cyanobacteria, including those that form stromatolites - nitrogen fixing bacteria - methanogens - deep-sea bacteria ...
Chapter 9: An Introduction to Taxonomy: The Bacteria
... Binomial Nomenclature • The system used to name all living things • The first name designates the genus (plural: genera) and its first letter is capitalized • The second name is the specific epithet, and it is not capitalized • Together the genus and specific epithet identify the species The Meaning ...
... Binomial Nomenclature • The system used to name all living things • The first name designates the genus (plural: genera) and its first letter is capitalized • The second name is the specific epithet, and it is not capitalized • Together the genus and specific epithet identify the species The Meaning ...
Archaea
... simplest, most primitive forms of life • Oldest fossils ever found (3.8 billion years old) appear similar to Archaea • Archaea are prokaryotes, unicellular organisms that lack a nucleus and other membrane-bound organelles • Thought to have had an important role in the early evolution of life ...
... simplest, most primitive forms of life • Oldest fossils ever found (3.8 billion years old) appear similar to Archaea • Archaea are prokaryotes, unicellular organisms that lack a nucleus and other membrane-bound organelles • Thought to have had an important role in the early evolution of life ...
Archaea
The Archaea (/ɑrˈkiːə/ or /ɑrˈkeɪə/ ar-KEE-ə or ar-KAY-ə; singular archaeon) constitute a domain or kingdom of single-celled microorganisms. These microbes are prokaryotes, meaning that they have no cell nucleus or any other membrane-bound organelles in their cells.Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebacteria kingdom), but this classification is outdated. Archaeal cells have unique properties separating them from the other two domains of life, Bacteria and Eukaryota. The Archaea are further divided into four recognized phyla. Classification is difficult because the majority have not been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from their environment.Archaea and bacteria are generally similar in size and shape, although a few archaea have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably the enzymes involved in transcription and translation. Other aspects of archaeal biochemistry are unique, such as their reliance on ether lipids in their cell membranes. Archaea use more energy sources than eukaryotes: these range from organic compounds, such as sugars, to ammonia, metal ions or even hydrogen gas. Salt-tolerant archaea (the Haloarchaea) use sunlight as an energy source, and other species of archaea fix carbon; however, unlike plants and cyanobacteria, no known species of archaea does both. Archaea reproduce asexually by binary fission, fragmentation, or budding; unlike bacteria and eukaryotes, no known species forms spores.Archaea were initially viewed as extremophiles living in harsh environments, such as hot springs and salt lakes, but they have since been found in a broad range of habitats, including soils, oceans, marshlands and the human colon, oral cavity, and skin. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet. Archaea are a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit human and ruminant guts, where their vast numbers aid digestion. Methanogens are used in biogas production and sewage treatment, and enzymes from extremophile archaea that can endure high temperatures and organic solvents are exploited in biotechnology.