Unicellular organism: Difference between revisions

Revision as of 00:33, 10 February 2025

Organisms consisting of a single cell

Unicellular organisms are organisms that consist of a single cell, unlike multicellular organisms which are made up of multiple cells. Unicellular organisms can be either prokaryotic or eukaryotic.

Types of Unicellular Organisms

Prokaryotes

Prokaryotic unicellular organisms include bacteria and archaea. These organisms lack a nucleus and other membrane-bound organelles. Bacteria are found in virtually every habitat on Earth, from soil to water to the human body. Archaea, although similar in appearance to bacteria, have distinct genetic and biochemical characteristics.

Eukaryotes

Eukaryotic unicellular organisms include protists, algae, and some fungi. These organisms have a nucleus and other organelles enclosed within membranes. Examples include the Paramecium, a type of ciliate, and various species of unicellular algae such as diatoms.

Reproduction

Unicellular organisms reproduce in various ways, including binary fission, budding, and spore formation. In binary fission, the cell divides into two genetically identical cells. Budding involves the formation of a new organism from a small projection on the parent organism. Some unicellular organisms can also exchange genetic material through processes such as conjugation.

Ecological Role

Unicellular organisms play crucial roles in ecosystems. They are primary producers in many aquatic environments, forming the base of the food web. They also contribute to the nitrogen cycle and other biogeochemical cycles. Some unicellular organisms are pathogens, causing diseases in humans, animals, and plants.

Evolutionary Significance

Unicellular organisms are believed to be the earliest forms of life on Earth. Fossil evidence, such as stromatolites, suggests that unicellular life existed over 3.5 billion years ago. These organisms have evolved into a wide variety of forms, leading to the diversity of life seen today.

Gallery

Ventricaria ventricosa, a large unicellular alga
Stromatolites in Shark Bay, Western Australia
Bacteria with a capsule
Echinoderm larvae, an example of a multicellular organism
Paramecium tetraurelia, a ciliate
Diatom, a type of unicellular algae
Yeast, a unicellular fungus

Related pages

References

Madigan, M.T., Martinko, J.M., Bender, K.S., Buckley, D.H., & Stahl, D.A. (2014). Brock Biology of Microorganisms. Pearson.
Margulis, L., & Schwartz, K.V. (1998). Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth. W.H. Freeman.

@@ Line 1: / Line 1: @@
-'''Unicellular organism''' is an organism that consists of a single cell. This includes most life on Earth, with bacteria being the most numerous. Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. All life that has a cellular structure with a nucleus falls into the eukaryotic category, and life forms without a nucleus fall into the prokaryotic category.
+{{short description|Organisms consisting of a single cell}}
+{{Use dmy dates|date=October 2023}}
-== Characteristics ==
+'''Unicellular organisms''' are organisms that consist of a single [[cell (biology)|cell]], unlike [[multicellular organism|multicellular organisms]] which are made up of multiple cells. Unicellular organisms can be either [[prokaryote|prokaryotic]] or [[eukaryote|eukaryotic]].
-Unicellular organisms are usually microscopic, less than one tenth of a millimeter long. There are exceptions, such as the giant amoeba ''[[Chaos carolinense]]'', which can reach lengths of 5 mm, and the even larger ''[[Valonia ventricosa]]'', a species of algae which can reach 1 to 4 cm.
+==Types of Unicellular Organisms==
-== Classification ==
+===Prokaryotes===
+Prokaryotic unicellular organisms include [[bacteria]] and [[archaea]]. These organisms lack a [[cell nucleus|nucleus]] and other membrane-bound organelles. Bacteria are found in virtually every habitat on Earth, from soil to water to the human body. Archaea, although similar in appearance to bacteria, have distinct genetic and biochemical characteristics.
-Unicellular organisms are divided into two types: prokaryotic and eukaryotic organisms. Prokaryotes include bacteria and archaea, two of the three domains of life. Protozoans, most algae, and yeast are examples of eukaryotes.
+===Eukaryotes===
+Eukaryotic unicellular organisms include [[protists]], [[algae]], and some [[fungi]]. These organisms have a nucleus and other organelles enclosed within membranes. Examples include the [[Paramecium]], a type of [[ciliate]], and various species of [[unicellular algae]] such as [[diatoms]].
-== Reproduction ==
+==Reproduction==
+Unicellular organisms reproduce in various ways, including [[binary fission]], [[budding]], and [[spore]] formation. In binary fission, the cell divides into two genetically identical cells. Budding involves the formation of a new organism from a small projection on the parent organism. Some unicellular organisms can also exchange genetic material through processes such as [[conjugation (biology)|conjugation]].
-Unicellular organisms reproduce through a process called binary fission. During binary fission, the organism duplicates its genetic material, or deoxyribonucleic acid (DNA), and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA.
+==Ecological Role==
+Unicellular organisms play crucial roles in ecosystems. They are primary producers in many aquatic environments, forming the base of the food web. They also contribute to the [[nitrogen cycle]] and other biogeochemical cycles. Some unicellular organisms are pathogens, causing diseases in humans, animals, and plants.
-== Evolution ==
+==Evolutionary Significance==
+Unicellular organisms are believed to be the earliest forms of life on Earth. Fossil evidence, such as [[stromatolites]], suggests that unicellular life existed over 3.5 billion years ago. These organisms have evolved into a wide variety of forms, leading to the diversity of life seen today.
-Unicellular organisms are believed to be the first form of life on Earth, with early examples including the bacteria-like fossils found in Western Greenland that are about 3.5 billion years old.
+==Gallery==
+<gallery>
+File:Ventricaria_ventricosa.JPG|''[[Ventricaria ventricosa]]'', a large unicellular alga
+File:Stromatolites_in_Sharkbay.jpg|[[Stromatolites]] in Shark Bay, Western Australia
+File:Bacteria_with_capsule.jpg|[[Bacteria]] with a capsule
+File:Echinoderms_600.jpg|[[Echinoderm]] larvae, an example of a multicellular organism
+File:Paramecia_tetraurelia.jpeg|''[[Paramecium tetraurelia]]'', a ciliate
+File:CSIRO_ScienceImage_7632_SEM_diatom.jpg|[[Diatom]], a type of unicellular algae
+File:Kg3.jpg|[[Yeast]], a unicellular fungus
+</gallery>
-== See also ==
+==Related pages==
-* [[Cell (biology)]]
 * [[Multicellular organism]]
-* [[Colonial organism]]
+* [[Prokaryote]]
-* [[Superorganism]]
+* [[Eukaryote]]
+* [[Microorganism]]
-== References ==
+==References==
-<references />
+* Madigan, M.T., Martinko, J.M., Bender, K.S., Buckley, D.H., & Stahl, D.A. (2014). ''Brock Biology of Microorganisms''. Pearson.
+* Margulis, L., & Schwartz, K.V. (1998). ''Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth''. W.H. Freeman.
-[[Category:Cell biology]]
-[[Category:Microbiology]]
 [[Category:Unicellular organisms]]
-{{stub}}