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Paramecium reproduction is asexual, by binary fission, which has been characterized as "the sole mode of reproduction in ciliates" (conjugation being a sexual phenomenon, not directly resulting in increase of numbers). [3] [32] During fission, the macronucleus splits by a type of amitosis, and the micronuclei undergo mitosis. The cell then ...
In the former, the egg and sperm cells that unite come from the same flower. In the latter, the sperm and egg cells can come from a different flower on the same plant. While the latter method does blur the lines between autogamous self-fertilization and normal sexual reproduction, it is still considered autogamous self-fertilization. [10]
The cell then divides in two, and each new cell obtains a copy of the micronucleus and the macronucleus. Ciliate undergoing the last processes of binary fission Division of ciliate Colpidium Typically, the cell is divided transversally, with the anterior half of the ciliate (the proter ) forming one new organism, and the posterior half (the ...
Paramecium aurelia demonstrate a strong "sex reaction" whereby groups of individuals will cluster together, and emerge in conjugant pairs. This pairing can last up to 12 hours, during which the micronucleus of each organism will be exchanged. [3] In Paramecium aurelia, a cryptic species complex was discovered by observation. [4]
Paramecium tetraurelia, a ciliate, with discharged trichocysts (artificially colored in blue). A trichocyst is an organelle found in certain ciliates [1] [2] and dinoflagellates. [3] A trichocyst can be found in tetrahymena and along cila pathways of several metabolic systems.
The cell body is encircled by two ciliary bands, or pectinelles, an upper band and a lower band just below the midline. [4] This distinguishes them from the related genus Monodinium, which have only a single band, except during cell division. [5] The pectinelles are used to move Didinium through water by rotating the cell around its axis. [6]
Ciliates are a model alveolate, having been genetically studied in great depth over the longest period of any alveolate lineage. They are unusual among eukaryotes in that reproduction involves a micronucleus and a macronucleus. Their reproduction is easily studied in the lab, and made them a model eukaryote historically.
The cytostome forms an invagination on the cell surface and is typically directed towards the nucleus of the cell. [2] The cytostome is often labeled as the entire invagination, but in fact the cytostome only constitutes the opening of the invagination at the surface of the cell. The rest of the invagination is classified as the cytopharynx. [3]