Unicellular organisms
Unicellular Organisms
Unicellular organisms (pronunciation: /ˌjuːnɪsɛˈlʊlər ˈɔːɡənɪzəm/) are organisms that consist of a single cell. This is in contrast to multicellular organisms, which are composed of multiple cells. The etymology of the term comes from the Latin uni meaning "one" and cellula meaning "small room".
Characteristics
Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. Prokaryotes include bacteria and archaea. They do not have a nucleus and other membrane-bound organelles. Eukaryotes include protozoa, certain algae, and yeast. They have a nucleus and other membrane-bound organelles.
Examples
Some examples of unicellular organisms include the paramecium, amoeba, and euglena. These organisms are capable of all necessary life functions such as reproduction, digestion, and respiration within a single cell.
Importance
Unicellular organisms play a vital role in the biosphere. They are involved in nutrient cycles, and some can fix nitrogen from the atmosphere. They also form the base of the food chain in many ecosystems.
Related Terms
- Cell: The basic structural and functional unit of all known living organisms.
- Prokaryote: A unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle.
- Eukaryote: An organism whose cells contain a nucleus and other organelles enclosed within membranes.
- Multicellular organism: An organism that consists of more than one cell, in contrast to a unicellular organism.
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