3 Domain System of Classification

3 Domain System of Classification - They are characterized...

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3 Domain System of Classification The 3-domain system classifies all life in 3 domains – Bacteria, Archaea, and Eukarya. This system took over from the obsolete 5-kingdom system. It was developed using phylogenies based on molecular data, such as rRNA gene comparison. Bacteria – This domain contains most of the currently known Prokaryotes, including the bacteria most closely related to chloroplasts and mitochondria. Bacteria are characterized by; Membranes composed of unbranched fatty acid chains Cell wall contains peptidoglycan Growth inhibited by streptomycin and chloramphenicol Circular chromosomes Unique rRNA DNA is not wound around histones Protein synthesis is initiated by formyl methionine (fMet) Very rarely have introns in their genes Archaea – This domain consists of a diverse group of prokaryotes that inhabit a wide variety of environments. Some Archaea can use hydrogen as an energy source, and others can survive in extremely salty environments.
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Unformatted text preview: They are characterized by; Membranes composed of some branched fatty acid chains Cell walls dont contain peptidoglycan Growth is not inhibited by streptomycin and Circular chromosomes Unique rRNA In some species DNA is wound around histones Protein synthesis is initiated by methionine (Met) Sometimes have introns in their genes Eukarya This domain consists of all the organisms that have true nuclei. This includes many single-celled organisms, as well as multicellular plants, fungi, and animals. Eukarya are characterized by; Membranes composed of unbranched fatty acid chains Those Eukarya with cell walls dont contain peptidoglycan Resistant to the effects of streptomycin and Linear chromosomes Unique rRNA DNA wound around histones Protein synthesis is initiated by methionine (Met) Introns present in genes (in all but very rare exceptions)...
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