Acetabularia
| Acetabularia | |
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| Scientific classification | |
| Kingdom: | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Ulvophyceae |
| Order: | Dasycladales |
| Family: | Polyphysaceae |
| Genus: |
Acetabularia Lamouroux, 1812 |
| Species | |
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Acetabularia is a genus of green algae, specifically of the Polyphysaceae family, Typically found in subtropical waters, Acetabularia is a single-celled organism, but gigantic in size and complex in form, making it an excellent model organism for studying cell biology. In form, the mature Acetabularia resembles the round leaves of a nasturtium, is 0.5 to 10 cm tall and has three anatomical parts: a bottom rhizoid that resembles a set of short roots; a long stalk in the middle; and a top umbrella of branches that may fuse into a cap. The single nucleus of Acetabularia is located in the rhizoid, and allows the cell to regenerate completely if its cap is removed. The caps of two Acetabularia may also be exchanged, even from two different species. In addition, if a piece of the stem is removed, with no access to the nucleus in the rhizoid, this isolated stem piece will also grow a new cap.
In the 1930s–1950s Joachim Hämmerling conducted experiments in which he demonstrated Acetabularia's genetic information is contained in the nucleus. This was the first demonstration that genes are encoded by DNA in eukaryotes; earlier studies by Oswald Avery and others had shown that this was true for prokaryotes.
The name, Acetabularia, derives from the Latin word acetabulum, a broad, shallow cup used for dipping bread; the upturned cap of Acetabularia resembles such a cup. For this reason, it is also sometimes called mermaid's wineglass.
In the 19th century the same designation Acetabularia was proposed by George Edward Massee for a genus of fungi (now Cyphellopus), but this usage is obsolete and considered invalid as the algal name takes precedence.
Acetabularia has three basic parts: its rhizoid, a short set of root-like appendages that contain the nucleus and anchor the cell to fissures in a substrate; its median stalk, which accounts for most of its length; and its apex, where its cap forms. There are usually several whorls of hair-like appendages close to the apex.
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