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eukaryote
eukaryote , a cell or organism composed of cells that have a membrane-bound nucleus and organelles (mitochondria, chloroplasts; see cell , in biology) and genetic material organized in chromosomes in which the DNA is combined with histone proteins. Eukaryotes are contrasted with the prokaryotes (...
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Monera
Monera taxonomic kingdom that comprises the prokaryotes ( bacteria and cyanobacteria ). Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and usually lack membrane-bound organelles (mitochondria, chloroplasts; see cell , in biology). They have a small ring of DNA as thei...
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cyanobacteria
cyanobacteria or blue-green algae, photosynthetic bacteria that contain chlorophyll. For many years they were classified in the plant kingdom along with algae , but discoveries made possible by the electron microscope and new biochemical techniques have shown them to be prokaryotes more simi...
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Archaebacteria
Archaebacteria , diverse group of bacteria (prokaryotes), sometimes called the archaea and considered a major group unto themselves. Archaebacteria are contrasted with the Eubacteria, from which they differ biochemically in the arrangement of the bases in their ribosomal RNA and in the composition...
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Protista
Protista or Protoctista , in the five-kingdom system of classification, a kingdom comprising a variety of unicellular and some simple multinuclear and multicellular eukaryotic organisms. Protists, which are eukaryotes , have cells that have a membrane-bound nucleus, DNA that is associated with ...
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cell
cell in biology, the unit of structure and function of which all plants and animals are composed. The cell is the smallest unit in the living organism that is capable of integrating the essential life processes. There are many unicellular organisms, e.g., bacteria and protozoans , in which the s...
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animal
animal any member of the animal kingdom (kingdom Animalia), as distinguished from organisms of the plant kingdom (kingdom Plantae) and the kingdoms Fungi , Protista , and Monera in the five-kingdom system of classification. (Another classification system, suggested by genetic sequencing studi...
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Ribosome
Ribosome
Ribosomes are the cellular organelles that carry out protein synthesis, through a process called translation . They are found in both prokaryotes and eukaryotes , these molecular machines are responsible for accurately translating the linear genetic code, via the messenger RNA, into ...
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algae
algae [plural of Lat. alga =seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that lack true roots, stems, leaves, and flowers). More recently, most alg...
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streptococcus
streptococcus , any of a group of gram-positive bacteria, genus Streptococcus, some of which cause disease. Streptococci are spherical and divide by fission, but they remain attached and so grow in beadlike chains. The incidence and severity of streptococcal diseases decreased dramatically after t...
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