Chlamydomonas globosa - 400x (13263097835)

''Chlamydomonas'' is a genus of green algae consisting of about 150 speciesSmith, G.M. 1955 ''Cryptogamic Botany Volume 1. Algae and Fungi'' McGraw-Hill Book Company Inc of unicellular

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and thei ...

s, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". ''Chlamydomonas'' is used as a

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

for

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and phys ...

, especially studies of flagellar motility and

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it i ...

dynamics, biogenesis, and genetics. One of the many striking features of ''Chlamydomonas'' is that it contains

ion channel Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ...

s ( channelrhodopsins) that are directly activated by light.

Some Some may refer to: *''some'', an English word used as a determiner and pronoun; see use of ''some'' *The term associated with the existential quantifier *"Some", a song by Built to Spill from their 1994 album ''There's Nothing Wrong with Love'' * ...

regulatory systems of ''Chlamydomonas'' are more complex than their homologs in

Gymnosperms The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν� ...

, with evolutionarily related regulatory proteins being larger and containing additional domains. Molecular phylogeny studies indicated that the traditional genus ''Chlamydomonas'' as defined using morphological data was polyphyletic within Volvocales. Many species were subsequently reclassified (e.g., in ''

Oogamochlamys ''Oogamochlamys'' is a genus of green algae in the family Chlamydomonadaceae.See the NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National In ...

, Lobochlamys''), and many other "''Chlamydomonas''" s.l. lineages are still to be reclassified.

Description

All ''Chlamydomonas'' are unicellular organisms, spherical or slightly cylindrical, and a papilla may be present or absent. Chloroplasts are green and usually cup-shaped. Guiry, M.D., John, D.M. Rindi, F. and McCarthy, T.K. (ed) ''2007 New Survey of Clare Island Volume 6: The Freshwater and Terrestrial Algae''. Royal Irish Academy. A key feature of the genus is its two anterior flagella, each as long as the other. The flagellar

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 1 ...

s may each be disassembled by the cell to provide spare material to rebuild the other's microtubules if they are damaged.

Species

*''Chlamydomonas acidophila'' * ''Chlamydomonas caudata'' Wille * ''Chlamydomonas ehrenbergii'' Gorozhankin * '' Chlamydomonas elegans'' G.S.West 1915 * ''Chlamydomonas moewusii'' * '' Chlamydomonas nivalis'' * ''Chlamydomonas ovoidae'' * '' Chlamydomonas reinhardtii''

Ecology

''Chlamydomonas'' is widely distributed in freshwater or damp soil. It is generally found in a habitat rich in ammonium salt. It possesses red eye spots for photosensitivity and reproduces both asexually and sexually. ''Chlamydomonass asexual reproduction occurs by zoospores, aplanospores, hypnospores, or a palmella stage, while its sexual reproduction is through

isogamy Isogamy is a form of sexual reproduction that involves gametes of the same morphology (indistinguishable in shape and size), found in most unicellular eukaryotes. Because both gametes look alike, they generally cannot be classified as male or ...

anisogamy Different forms of anisogamy: A) anisogamy of motile cells, B) egg_cell.html"_;"title="oogamy_(egg_cell">oogamy_(egg_cell_and_sperm_cell),_C)_anisogamy_of_non-motile_cells_(egg_cell_and_spermatia)..html" ;"title="egg_cell_and_sperm_cell.html" ;" ...

or oogamy.

Nutrition

Most species are obligate phototrophs but '' C. reinhardtii'' and ''C. dysostosis'' are facultative heterotrophs that can grow in the dark in the presence of acetate as a carbon source.

Morphology

* Motile unicellular algae. * Generally oval and/or circular. * Cell wall is made up of a glycoprotein and non-cellulosic polysaccharides instead of cellulose. * Two anteriorly inserted whiplash flagella. Each flagellum originates from a basal granule in the anterior papillate or non-papillate region of the cytoplasm. Each flagellum shows a typical 9+2 arrangement of the component fibrils. * Contractile vacuoles are near the bases of flagella. * Prominent cup or bowl-shaped chloroplast is present. The chloroplast contains bands composed of a variable number of the photosynthetic thylakoids which are not organised into grana-like structures. * The nucleus is enclosed in a cup-shaped chloroplast, which has a single large pyrenoid where starch is formed from photosynthetic products. Pyrenoid with starch sheath is present in the posterior end of the chloroplast. * Eye spot present in the anterior portion of the chloroplast. It consists of two or three, more or less parallel rows of linearly arranged fat droplets.

Uses

Some ''Chlamydomonas'' are edible.

References

External links

''Chlamydomonas'' Center

''Chlamydomonas reinhardtii'' Transcription Factor Database

3D electron microscopy structures of Chlamydomonas-related proteins at the EM Data Bank(EMDB)

The Seaweed Site

Ancient gene family protects algae from salt and cold in an Antarctic lake
on: EurekAlert!, 20-Aug-2020, on species UWO241 and in Lake Bonney (Antarctica) {{Taxonbar, from=Q133008 Chlamydomonadales genera Chlamydomonadaceae Taxa named by Christian Gottfried Ehrenberg