Symbiogenesis
According to Margulis and Sagan,[1] "Life did not take over the globe by combat, but by networking" (i.e., by cooperation)[2].
The possibility that peroxisomes may have an endosymbiotic origin has also been considered, although they lack DNA. Christian de Duve proposed that they may have been the first endosymbionts, allowing cells to withstand growing amounts of free molecular oxygen in the Earth's atmosphere. However, it now appears that they may be formed de novo, contradicting the idea that they have a symbiotic origin.[3]
It is also believed that these endosymbionts transferred some of their own DNA to the host cell's nucleus during the evolutionary transition from a symbiotic community to an instituted eukaryotic cell. This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between prokaryotic species, even if they are not closely related. Prokaryotes can take up DNA from their surroundings and have a limited ability to incorporate it into their own genome.
Evidence
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chlorarachniophytes). The two additional membranes are thought to correspond to the plasma membrane of the engulfed alga and the phagosomal membrane of the host cell. The endosymbiotic acquisition of a eukaryote cell is represented in the cryptophytes; where the remnant nucleus of the red algal symbiont (the nucleomorph) is present between the two inner and two outer plastid membranes.[citation needed]
Despite the diversity of organisms containing plastids, the morphology, biochemistry, genomic organisation, and molecular phylogeny of plastid RNAs and proteins suggest a single origin of all extant plastids – although this theory is still debated.[4][5]
Problems
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Notes
- ^ Margulis, Lynn (2001). "Marvellous microbes". Resurgence. 206: 10–12.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Witzany G (2006). "Serial Endosymbiotic Theory (SET): The Biosemiotic Update". Acta Biotheoretica. 54 (1): 103–17. doi:10.1007/s10441-006-7831-x.
- ^ Gabaldón T, Snel B, van Zimmeren F, Hemrika W, Tabak H, Huynen MA (2006). "Origin and evolution of the peroxisomal proteome". Biol. Direct. 1: 8. doi:10.1186/1745-6150-1-8. PMC 1472686. PMID 16556314.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) (Provides evidence that contradicts an endosymbiotic origin of peroxisomes. Instead it is suggested that they evolutionarily originate from the Endoplasmic Reticulum) - ^ McFadden GI, van Dooren GG (2004). "Evolution: red algal genome affirms a common origin of all plastids". Curr. Biol. 14 (13): R514–6. doi:10.1016/j.cub.2004.06.041. PMID 15242632.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Gould SB, Waller RF, McFadden GI (2008). "Plastid evolution". Annu Rev Plant Biol. 59: 491–517. doi:10.1146/annurev.arplant.59.032607.092915. PMID 18315522.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
References
- Alberts, Bruce (2002). Molecular biology of the cell. New York: Garland Science. ISBN 0-8153-3218-1. (General textbook)
- Blanchard JL, Lynch M (2000). "Organellar genes: why do they end up in the nucleus?". Trends Genet. 16 (7): 315–20. doi:10.1016/S0168-9525(00)02053-9. PMID 10858662.
{{cite journal}}: Unknown parameter|month=ignored (help) (Discusses theories on how mitochondria and chloroplast genes are transferred into the nucleus, and also what steps a gene needs to go through in order to complete this process.) - Jarvis P (2001). "Intracellular signalling: the chloroplast talks!". Curr. Biol. 11 (8): R307–10. doi:10.1016/S0960-9822(01)00171-3. PMID 11369220.
{{cite journal}}: Unknown parameter|month=ignored (help) (Recounts evidence that chloroplast-encoded proteins affect transcription of nuclear genes, as opposed to the more well-documented cases of nuclear-encoded proteins that affect mitochondria or chloroplasts.) - Brinkman FS; Blanchard JL; Cherkasov A; et al. (2002). "Evidence that plant-like genes in Chlamydia species reflect an ancestral relationship between Chlamydiaceae, cyanobacteria, and the chloroplast". Genome Res. 12 (8): 1159–67. doi:10.1101/gr.341802. PMC 186644. PMID 12176923.
{{cite journal}}: Explicit use of et al. in:|author3=(help); Unknown parameter|author-separator=ignored (help); Unknown parameter|month=ignored (help)CS1 maint: extra punctuation (link) - Okamoto N, Inouye I (2005). "A secondary symbiosis in progress?". Science. 310 (5746): 287. doi:10.1126/science.1116125. PMID 16224014.
{{cite journal}}: Unknown parameter|month=ignored (help) - Cohen WD, Gardner RS (1959). "Viral Theory and Endosymbiosis" (PDF). (Discusses theory of origin of eukaryotic cells by incorporating mitochondria and chloroplasts into anaerobic cells with emphasis on 'phage bacterial and putative viral mitochondrial/chloroplast interactions.)