Chromatophore (organelle)
As a chromatophore (from ancient Greek χρωμάτιον chromate , Pigment 'and φορός Phoros , carrying') in which is cell biology of the pigment-bearing portion of a cell refers to the as invagination of the cell membrane into the cytoplasm or as a closed Membranumhülle a private cellular compartment or an organelle represents. Such a chromatophore is found in some bacterial cells and plant cells.
Chromatophores of phototrophic bacteria
Chromatophores occur in various phototrophic bacteria and carry membrane-based pigments for photosynthesis or a photosystem , for example in purple bacteria and cyanobacteria .
The photosynthetic compartments of photosynthetic bacteria are intraplasmic membranes that emerge from the cytoplasmic membrane . They can fill the interior of the cell like vesicles or, if they are very flattened, they can also form stacks. These membranes represent a matrix for the arrangement of the embedded photosynthetic pigments. The chromatophores are therefore carriers of the components of photosynthetic electron transport and photophosphorylation.
Chromatophores as colored plastids in eukaryotes
Chromatophores also occur as organelles in plant cells . With an older collective term, the colored plastids of a eukaryotic 'plant' cell are understood here, in particular chloroplasts (green) and chromoplasts . This also includes the gerontoplasts as old, degenerate plastids, which are colored yellow to red after the breakdown of chlorophyll (color of autumn leaves), as well as the phaeoplasts of brown algae and rhodoplasts of red algae .
The term chromatophore in this botanical sense was coined by Friedrich Schmitz in 1883 and is now considered obsolete. With today's knowledge of the exchange processes, the energy supply systems and the membrane structure of chloroplasts, especially the - similar to the mitochondrial - reduced genome, plastids are viewed differently against the background of the endosymbiotic theory and understood as having emerged from semiautonomous symbionts in cells .
Chromatophores in Paulinella
To the understanding of the evolution of phototrophic unicellular and colony-forming green algae and the further developed land plants , the proof has meanwhile contributed that, independently of this, an ancestor of the amoeboid Paulinella chromatophora ( Euglyphida ) succeeded in integrating a photosynthetically active bacterium into a eukaryotic cell so that it now is equipped with chromatophores and thus the ability to photosynthesize.
Other meanings
The term chromatophores is also used with a different meaning for pigment cells of tissue animals, the coloration, color pattern and color change of which are different depending on the number, distribution, and deformation of their color cells, which differ according to the type and amount of pigment.
See also
Web links
- Amoeba helps solve evolution puzzles around photosynthesis
- Evolution of a photosynthetic organelle - with microscopic images
Individual evidence
- ↑ see also Adolf Meyer-Abich: Contributions to the theory of the evolution of organisms. II: Type synthesis by holobiosis. Brill, Leyden 1950, p.91 .
- ^ Eva CM Nowack: Paulinella chromatophora - a Model for the Acquisition of Photosynthesis by Eukaryotes. (Dissertation abstract). University of Cologne 2008, short summary, pdf (90 kB).
- ↑ Takuro Nakayama, John M. Archibald: Evolving a photosynthetic organelle . In: BMC Biology . 10, No. 1, 2012, p. 35. doi : 10.1186 / 1741-7007-10-35 . PMID 22531210 . PMC 3337241 (free full text).
- ↑ ECM Nowack, H. Vogel, M. Groth, AR Grossman, M. Melkonian, G. Glöckner: Endosymbiotic Gene Transfer and Transcriptional Regulation of Transferred Genes in Paulinella chromatophora . In: Molecular Biology and Evolution . 28, No. 1, 2010, pp. 407-22. doi : 10.1093 / molbev / msq209 . PMID 20702568 .
- ↑ Wilfried Probst: Early Evolution and Symbiosis , European University Flensburg, Institute for Biology and Science and its Didactics: § On the way to chloroplast formation, accessed on April 19, 2019