unicellular organism
Unicellular organism
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"Single-celled" redirects here. For prison cell assignment, see Single-celling.
Valonia ventricosa is among the largest unicellular species.
A unicellular organism, also known as a single-celled organism, is an organism that consists of only one cell, unlike a multicellular organism that consists of multiple cells. Historically the simple single celled organisms have sometimes been referred to as monads.[1] The main groups of unicellular organisms are bacteria, archaea, protozoa, unicellular algae and unicellular fungi. Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms.Unicellular organisms are believed to be the oldest form of life, possibly existing 3.8 billion years ago.[2]
Prokaryotes, most protists, and some fungi are unicellular. Although some of these organisms live in colonies, they are still unicellular. These organisms live together, and each cell in the colony is the same. However, each cell must carry out all life processes in order for that cell to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other in order to survive.
Some organisms are partially uni- and multicellular, like Dictyostelium discoideum. Other can be unicellular and multinucleate, like Myxogastria and Plasmodium.
‘Candidatus Magnetoglobus multicellularis’, related to Deltaproteobacteria, is a multicellular prokaryote. It is neither unicellular, nor a colony.
Most unicellular organisms are of microscopic size and are thus classified as microorganisms. However, some unicellular protists and bacteria are macroscopic and visible to the naked eye.[3] Examples include:
Xenophyophores, protozoans of the phylum Foraminifera, are the largest examples known, with Syringammina fragilissima achieving a diameter of up to 20 cm.[4]
Nummulite, foraminiferans
Valonia ventricosa, an alga of the class
From Wikipedia, the free encyclopedia
Jump to: navigation, search
"Single-celled" redirects here. For prison cell assignment, see Single-celling.
Valonia ventricosa is among the largest unicellular species.
A unicellular organism, also known as a single-celled organism, is an organism that consists of only one cell, unlike a multicellular organism that consists of multiple cells. Historically the simple single celled organisms have sometimes been referred to as monads.[1] The main groups of unicellular organisms are bacteria, archaea, protozoa, unicellular algae and unicellular fungi. Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms.Unicellular organisms are believed to be the oldest form of life, possibly existing 3.8 billion years ago.[2]
Prokaryotes, most protists, and some fungi are unicellular. Although some of these organisms live in colonies, they are still unicellular. These organisms live together, and each cell in the colony is the same. However, each cell must carry out all life processes in order for that cell to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other in order to survive.
Some organisms are partially uni- and multicellular, like Dictyostelium discoideum. Other can be unicellular and multinucleate, like Myxogastria and Plasmodium.
‘Candidatus Magnetoglobus multicellularis’, related to Deltaproteobacteria, is a multicellular prokaryote. It is neither unicellular, nor a colony.
Most unicellular organisms are of microscopic size and are thus classified as microorganisms. However, some unicellular protists and bacteria are macroscopic and visible to the naked eye.[3] Examples include:
Xenophyophores, protozoans of the phylum Foraminifera, are the largest examples known, with Syringammina fragilissima achieving a diameter of up to 20 cm.[4]
Nummulite, foraminiferans
Valonia ventricosa, an alga of the class