Plastid
A plastid is a self-reproducing organelle of plants and algae. A plastome is the DNA genome of a plastid.[1]p341
Examples of plastids are:
- Chloroplasts: photosynthesis; other plastids may have developed from chloroplasts.
- Chromoplasts: pigment synthesis and storage.
- Leucoplasts: make terpenes such as resin.
Genetics and evolution [change]
Plastids are one of the many different types of organelles in the cell. In endosymbiont theory, plastids originated as cyanobacteria. This was first suggested by Mereschkowsky in 1905[2][3] after an observation by Schimper in 1883 that chloroplasts closely resemble cyanobacteria.[4]
Almost all chloroplasts are thought to derive directly or indirectly from a single endosymbiotic event.[5] Mitochondria also derive from symbiosis, but chloroplasts are found only in plants and protista. The chloroplast is surrounded by a double-layered composite membrane with an intermembrane space; further, it has reticulations, or many infoldings, filling the inner spaces. The chloroplast has its own DNA, which codes for redox proteins involved in electron transport in photosynthesis.[6]
References [change]
- ↑ King R.C. Stansfield W.D. & Mulligan P.K. 2006. A dictionary of genetics, 7th ed. Oxford.
- ↑ Mereschkowsky C (1905). "Über Natur und Ursprung der Chromatophoren im Pflanzenreiche". Biol Centralbl 25: 593–604.
- ↑ Khakhina L.N. 1992. Concepts of symbiogenesis: a historical and critical survey of the research of Russian botanists. Yale, New Haven CN.
- ↑ Schimper AFW (1883). "Über die Entwicklung der Chlorophyllkörner und Farbkörper". Bot. Zeitung 41: 105–14, 121–31, 137–46, 153–62.
- ↑ Patrick J. Keeling (2004). "Diversity and evolutionary history of plastids and their hosts". American Journal of Botany 91: 1481–1493. doi:10.3732/ajb.91.10.1481. http://www.amjbot.org/cgi/content/full/91/10/z1481.
- ↑ Krause K (September 2008). "From chloroplasts to "cryptic" plastids: evolution of plastid genomes in parasitic plants". Curr. Genet. 54 (3): 111–21. doi:10.1007/s00294-008-0208-8. PMID 18696071.
