Difference between revisions of "Endosymbiotic hypothesis"

Latest revision as of 03:28, June 30, 2011

The endosymbiotic theory, known to academics as the serial endosymbiosis theory (SET), is a scientific theory concerning the origins of mitochondria, plastids (e.g. chloroplasts), and nuclei in eukaryotic cells. According to this hypothesis, these organelles arose from free-living bacteria that were taken inside another cell as endosymbionts.

Creation science critique of the edosymbiotic hypothesis

Dr. Carl Wieland is the Managing Director of Creation Ministries International

Citing a biology textbook Creation Ministries International writes:

“

Sometimes it is stated more cautiously:

‘In the endosymbiont theory, the ancestor of the eukaryotic cell (we will call this organism a protoeukaryote) is presumed to have been a large, anaerobic, heterotrophic prokaryote that obtained its energy by a glycolytic pathway. Unlike present-day bacteria, this organism had the ability to take up particulate matter … . The endosymbiont theory postulates that a condition arose in which a large, particularly complex, anaerobic prokaryote took up a small aerobic prokaryote into its cytoplasm and retained it in a permanent state [emphasis added].’

Whichever way it is stated, it is given an aura of authority and certainty by its frequent repetition in writings on cell biology. Many students find it convincing. However, like many evolutionary ideas, it may look solid from a distance, but gaps appear on close scrutiny.

The evidence for the endosymbiont theory revolves around selected similarities between mitochondria and bacteria, especially the DNA ring structure. However, these similarities do not prove evolutionary relationship. There is no clear pathway from any one kind of bacteria to mitochondria, although several types of bacteria share isolated points of similarity. Indeed, the scattered nature of these similarities has left plenty of room for a less-publicized ‘direct evolution’ theory of mitochondrial origin, in which they never had any free-living stage. There is enough diversity among the mitochondria of protozoa to make evolutionists wonder if endosymbiotic origin of mitochondria occurred more than once.

Mitochondrial DNA

The endosymbiont theory implies that there should be considerable autonomy for mitochondria. This is not the case. Mitochondria are far from self-sufficient even in their DNA, which is their most autonomous feature. Mitochondria actually have most of their proteins coded by nuclear genes, including their DNA synthesis enzymes.^[1]

”

Homology

Ernst Haeckel's homology arguments were later shown to be erroneous evolutionary speculation and a fraud. Please see: Theory of Evolution and Cases of Fraud, Hoaxes and Speculation

See also: Homology

Creation scientists and creationists argue that similarity is not just explainable by creation, but predicted. Christian apologist JP Holding explains:

“

Homologous structures, far from pointing away from a designer of infinite wisdom, would have indicated to readers of the Bible in their time a designer who did indeed possess infinite wisdom and mastery over His creation. It is only because modern persons have arbitrarily decided that a certain degree of what they see as ‘originality’ is a proper means value that the evolutionists’ argument carries any apparent force.

To frame our argument against the evolutionists’ misuse of homologous structures requires us to have an understanding of certain values critical to ancient persons. Roman literature of the New Testament period tells us that ‘(t)he primary test of truth in religious matters was custom and tradition, the practices of the ancients.’ In other words, old was good, and innovation was bad. Change or novelty was ‘a means value which serves to innovate or subvert core and secondary values.’

By itself, this demolishes one part of the evolutionists’ argument and makes it, clearly, a case of arbitrary imposition of modern values. In a context such as the above, ‘radically different design’ would have indicated to an ancient reader either no deity, or else a deity whose means was chaos and instability, or a deity who did not have mastery over creation.^[2]

”

Problems

Neither mitochondria nor plastids can survive in oxygen or outside the cell, having lost many essential genes required for survival.
A large cell, especially one equipped for phagocytosis, has vast energetic requirements, which cannot be achieved without the internalisation of energy production (due to the decrease in the surface area to volume ratio as size increases).

History

Dr. Tim White, anthropologist at the University of California-Berkeley, gave the name "Flipperpithecus" to a supposed "humanoid species" arising from a fossil find that is most likely part of a dolphin's rib. Evolutionary homology arguments are based on poor analysis and errant evolutionary preconceptions.

The endosymbiotic hypothesis was first articulated by famed Russian botanist Konstantin Mereschkowski in 1905^[3]. Mereschkowski based his theory in part on work done by botanist Andreas Schimper, who had observed in 1883 that the division of chloroplasts in green plants closely resembled that of cyanobacteria. Schimper had himself tentatively proposed (in a footnote) that green plants could have arisen from the symbiosis of two simpler organisms.^[4] In the 1920s, Irvin Wallin, a professor at the University of Colorado Medical School, extended the idea of an endosymbiotic origin to the mitochondria.^[5] These theories were initially dismissed (or ignored) by the scientific community, but later became fashionable within the evolutionist community.

The endosymbiotic hypothesis was advanced in 1967 by American biologist Lynn Margulis. A young faculty member at Boston University, Margulis authored a theoretical paper entitled The Origin of Mitosing Eukaryotic Cells^[6]. The paper, however, was "rejected by about fifteen scientific journals," Margulis recalled^[7]. It was finally accepted by The Journal of Theoretical Biology.

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. It is believed by evolutionists that over millennia 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 (called "serial endosymbiosis"). This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between bacteria species, even if they are not closely related. Bacteria can take up DNA from their surroundings and have a limited ability to incorporate it into their own genome.

References

↑ Mitochondria—created to energize us
↑ Holding, 2006
↑ Mereschkowski C (1905). "Über Natur und Ursprung der Chromatophoren im Pflanzenreiche". Biol Centralbl 25: 593–604.
↑ Schimper AFW (1883). "Über die Entwicklung der Chlorophyllkörner und Farbkörper". Bot. Zeitung 41: 105–14, 121–31, 137–46, 153–62.
↑ Wallin IE (1923). "The Mitochondria Problem". The American Naturalist 57 (650): 255–61. doi:10.1086/279919.
↑ Lynn Sagan (1967). "On the origin of mitosing cells". J Theor Bio. 14 (3): 255–274. doi:10.1016/0022-5193(67)90079-3. PMID 11541392.
↑ John Brockman, The Third Culture, New York: Touchstone, 1995, 135.

[1] Mitochondria—created to energize us

[2] Holding, 2006

[3] Mereschkowski C (1905). "Über Natur und Ursprung der Chromatophoren im Pflanzenreiche". Biol Centralbl 25: 593–604.

[4] Schimper AFW (1883). "Über die Entwicklung der Chlorophyllkörner und Farbkörper". Bot. Zeitung 41: 105–14, 121–31, 137–46, 153–62.

[5] Wallin IE (1923). "The Mitochondria Problem". The American Naturalist 57 (650): 255–61. doi:10.1086/279919.

[6] Lynn Sagan (1967). "On the origin of mitosing cells". J Theor Bio. 14 (3): 255–274. doi:10.1016/0022-5193(67)90079-3. PMID 11541392.

[7] John Brockman, The Third Culture, New York: Touchstone, 1995, 135.

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@@ Line 3: / Line 3: @@
 to this hypothesis, these organelles arose from free-living bacteria that were taken inside another cell as endosymbionts.
 == Creation science critique of the edosymbiotic hypothesis ==
-[[Image:Carl weiland.jpg|thumbnail|150px|right|Dr. [[Carl Wieland]] is the Managing Director of [[Creation Ministries International]] ]]
+[[Image:Carl weiland.jpg|thumbnail|225px|right|Dr. [[Carl Wieland]] is the Managing Director of [[Creation Ministries International]] ]]
 Citing a biology textbook [[Creation Ministries International]] writes:
 {{cquote|Sometimes it is stated more cautiously:
@@ Line 15: / Line 15: @@
 Mitochondrial DNA
-The endosymbiont theory implies that there should be considerable autonomy for mitochondria. This is not the case. Mitochondria are far from self-sufficient even in their DNA, which is their most autonomous feature. Mitochondria actually have most of their proteins coded by nuclear genes, including their DNA synthesis enzymes.<ref>http://creation.com/mitochondria-created-to-energize-us</ref>}}
+The endosymbiont theory implies that there should be considerable autonomy for mitochondria. This is not the case. Mitochondria are far from self-sufficient even in their DNA, which is their most autonomous feature. Mitochondria actually have most of their proteins coded by nuclear genes, including their DNA synthesis enzymes.<ref>[http://creation.com/mitochondria-created-to-energize-us Mitochondria—created to energize us]</ref>}}
+=== Homology ===
+[[Image:Haeckel.jpg|right|250px|thumb|[[Ernst Haeckel]]'s [[homology]] arguments were later shown to be erroneous evolutionary speculation and a fraud. Please see: [[Theory of Evolution and Cases of Fraud, Hoaxes and Speculation]]]]
+''See also:'' [[Homology]]
+[[Creation science|Creation scientists]] and [[creationism|creationists]] argue that similarity is not just explainable by [[creation]], but predicted.  [[Christian apologetics|Christian apologist]] [[JP Holding]] explains:
+{{cquote|Homologous structures, far from pointing away from a designer of infinite wisdom, would have indicated to readers of the [[Bible]] in their time [[Intelligent design|a designer]] who did indeed possess infinite wisdom and mastery over His creation. It is only because modern persons have arbitrarily decided that a certain degree of what they see as ‘originality’ is a proper means value that the evolutionists’ argument carries any apparent force.
+To frame our argument against the evolutionists’ misuse of homologous structures requires us to have an understanding of certain values critical to ancient persons. Roman literature of the New Testament period tells us that ‘(t)he primary test of truth in religious matters was custom and tradition, the practices of the ancients.’ In other words, old was good, and innovation was bad. Change or novelty was ‘a means value which serves to innovate or subvert core and secondary values.’
+By itself, this demolishes one part of the evolutionists’ argument and makes it, clearly, a case of arbitrary imposition of modern values. In a context such as the above, ‘radically different design’ would have indicated to an ancient reader either no deity, or else a deity whose means was chaos and instability, or a deity who did not have mastery over creation.<ref>Holding, 2006</ref>}}
 == Problems ==
-[[Image:Haeckel.jpg|right|200px|thumb|[[Ernst Haeckel]]'s [[homology]] arguments were later shown to be erroneous evolutionary speculation and a fraud.]]
-* Neither mitochondria nor plastids can survive in oxygen or outside the cell, having lost many essential genes required for survival. The standard counterargument points to the large timespan that the mitochondria/plastids have co-existed with their hosts. In this view, genes and systems that were no longer necessary were simply deleted, or in many cases, transferred into the host genome instead. (In fact these transfers constitute an important way for the host cell to regulate plastid or mitochondrial activity.) For example, most plastids are not able to produce respiratory proteins necessary for respiration. Like any living cell, plastids would die if energy is not provided to them by respiration.
-* A large cell, especially one equipped for phagocytosis, has vast energetic requirements, which cannot be achieved without the internalisation of energy production (due to the decrease in the surface area to volume ratio as size increases). This implies that, for the cell to gain mitochondria, it could not have been a eukaryote, and must have been a bacterium. This in turn implies that the emergence of the eukaryotes and the formation of mitochondria were achieved simultaneously. This may be explained by possibly a very close symbiotic relationship between two types of bacteria which eventually led to gene exchange and engulfing of the mitochondria precursors through partial fusion or engulfing by the host bacteria.
-* Genetic analysis of small eukaryotes that lack mitochondria shows that they all still retain genes for mitochondrial proteins. This implies that all these eukaryotes once had mitochondria. This objection can be answered if, as suggested above, the origin of the eukaryotes coincided with the formation of mitochondria. Alternatively, we may postulate extinction of all other descendants of a mitochondrion-free ancestral eukaryote, perhaps due to competition from the symbiotic clade, or oxygen poisoning as levels continued to rise.
-These last two problems are accounted for by the [http://www.fbmc.fcen.uba.ar/materias/genmol/bibliografia-1/hipotesis%20del%20hidrogeno%20para%20el%20primer%20eucariota.pdf hydrogen hypothesis].
+''See also:'' [[Theory of Evolution and Cases of Fraud, Hoaxes and Speculation]] and [[Creation science]] and [[Intelligent design]]
+* Neither mitochondria nor plastids can survive in oxygen or outside the cell, having lost many essential genes required for survival.
+* A large cell, especially one equipped for phagocytosis, has vast energetic requirements, which cannot be achieved without the internalisation of energy production (due to the decrease in the surface area to volume ratio as size increases).
 == History ==
+[[Image:Dolphin.jpg|thumb|200px|right|Dr. Tim White, anthropologist at the University of California-Berkeley, gave the name "[[Flipperpithecus]]" to a supposed "humanoid species" arising from a fossil find that is most likely part of a dolphin's rib. Evolutionary [[homology]] arguments are based on poor analysis and errant evolutionary preconceptions. ]]
+''See also:'' [[Theory of Evolution and Cases of Fraud, Hoaxes and Speculation]] and [[Creation science]] and [[Intelligent design]]
-The endosymbiotic theory was first articulated by famed [[Russian]] botanist Konstantin Mereschkowski in 1905<ref>Mereschkowski C (1905). "Über Natur und Ursprung der Chromatophoren im Pflanzenreiche". Biol Centralbl 25: 593–604.</ref>. Mereschkowski based his theory in part on work done by botanist Andreas Schimper, who had observed in 1883 that the division of chloroplasts in green [[plants]] closely resembled that of cyanobacteria. Schimper had himself tentatively proposed (in a footnote) that green plants could have arisen from the symbiosis of two simpler organisms.<ref>Schimper AFW (1883). "Über die Entwicklung der Chlorophyllkörner und Farbkörper". Bot. Zeitung 41: 105–14, 121–31, 137–46, 153–62.</ref> In the 1920s, Irvin Wallin, a [[professor]] at the University of Colorado Medical School, extended the idea of an endosymbiotic origin to the mitochondria.<ref>Wallin IE (1923). "The Mitochondria Problem". The American Naturalist 57 (650): 255–61. doi:10.1086/279919.
+The endosymbiotic hypothesis was first articulated by famed [[Russian]] botanist Konstantin Mereschkowski in 1905<ref>Mereschkowski C (1905). "Über Natur und Ursprung der Chromatophoren im Pflanzenreiche". Biol Centralbl 25: 593–604.</ref>. Mereschkowski based his theory in part on work done by botanist Andreas Schimper, who had observed in 1883 that the division of chloroplasts in green [[plants]] closely resembled that of cyanobacteria. Schimper had himself tentatively proposed (in a footnote) that green plants could have arisen from the symbiosis of two simpler organisms.<ref>Schimper AFW (1883). "Über die Entwicklung der Chlorophyllkörner und Farbkörper". Bot. Zeitung 41: 105–14, 121–31, 137–46, 153–62.</ref> In the 1920s, Irvin Wallin, a [[professor]] at the University of Colorado Medical School, extended the idea of an endosymbiotic origin to the mitochondria.<ref>Wallin IE (1923). "The Mitochondria Problem". The American Naturalist 57 (650): 255–61. doi:10.1086/279919.
-</ref> These theories were initially dismissed (or ignored) by the scientific community. More detailed electron microscopic comparisons between cyanobacteria and chloroplasts (for example, studies by Hans Ris<ref>Ris H, Singh RN (January 1961). "Electron microscope studies on blue-green algae". J Biophys Biochem Cytol 9 (1): 63–80. doi:10.1083/jcb.9.1.63. PMC 2224983. PMID 13741827.</ref>) combined with the discovery that plastids and mitochondria contain their own [[DNA]]<ref>Stocking C and Gifford E (1959). "Incorporation of thymidine into chloroplasts of Spirogyra". Biochem. Biophys. Res. Comm. 1 (3): 159–64. doi:10.1016/0006-291X(59)90010-5.
+</ref> These theories were initially dismissed (or ignored) by the scientific community, but later became fashionable within the [[evolution|evolutionist]] community.
-</ref> (which had recently been identified as the hereditary material of organisms) led to a resurrection of the idea in the 1960s.
-The endosymbiotic hypothesis was advanced and substantiated with [[microbiology|microbiological]] evidence in 1967 by [[American]] biologist Lynn Margulis. A young faculty member at [[Boston University]], Margulis authored a theoretical paper entitled ''The Origin of Mitosing Eukaryotic Cells''<ref>Lynn Sagan (1967). "On the origin of mitosing cells". J Theor Bio. 14 (3): 255–274. doi:10.1016/0022-5193(67)90079-3. PMID 11541392.</ref>. The paper, however, was "rejected by about fifteen scientific journals," Margulis recalled<ref>John Brockman, The Third Culture, New York: Touchstone, 1995, 135.</ref>(see [[Best of the Public]]). It was finally accepted by ''The Journal of Theoretical Biology'' and is considered today a landmark in modern endosymbiotic theory. Drawing heavily from the ideas of Mereschkowski and Wallin, Margulis's endosymbiotic theory formulation is the first to rely on direct microbiological observations as opposed to [[paleontology|paleontological]] or [[zoology|zoological]] observations, which were previously the norm for new works in [[evolutionary biology]].
+The endosymbiotic hypothesis was advanced in 1967 by [[American]] biologist Lynn Margulis. A young faculty member at [[Boston University]], Margulis authored a theoretical paper entitled ''The Origin of Mitosing Eukaryotic Cells''<ref>Lynn Sagan (1967). "On the origin of mitosing cells". J Theor Bio. 14 (3): 255–274. doi:10.1016/0022-5193(67)90079-3. PMID 11541392.</ref>. The paper, however, was "rejected by about fifteen scientific journals," Margulis recalled<ref>John Brockman, The Third Culture, New York: Touchstone, 1995, 135.</ref>. It was finally accepted by ''The Journal of Theoretical Biology''.
-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|Earth's]] atmosphere. However, it now appears that they may be formed ''de novo'', contradicting the idea that they have a symbiotic origin<ref>Gabaldón T, Snel B, van Zimmeren F, Hemrika W, Tabak H, Huynen MA (2006). "Origin and evolution of the peroxisomal proteome". Biol. Direct 1 (1): 8. doi:10.1186/1745-6150-1-8. PMC 1472686. PMID 16556314. (Provides evidence that contradicts an endosymbiotic origin of peroxisomes. Instead it is suggested that they evolutionarily originate from the Endoplasmic Reticulum)</ref>. It is believed that over millennia 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 (called "serial endosymbiosis"). This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between [[bacteria]] species, even if they are not closely related. Bacteria can take up DNA from their surroundings and have a limited ability to incorporate it into their own [[genome]].
+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|Earth's]] atmosphere. It is believed by [[evolution|evolutionists]] that over millennia 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 (called "serial endosymbiosis"). This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between [[bacteria]] species, even if they are not closely related. Bacteria can take up DNA from their surroundings and have a limited ability to incorporate it into their own [[genome]].
 == See Also ==
-* [[Theory of Evolution]]
+* [[Evolution]]
+* [[Origin of Life]]
 * [[Theory of Evolution and Cases of Fraud, Hoaxes and Speculation]]
 * [[Evolution, Liberalism, Atheism, and Irrationality]]