Endosymbiotic Theory: What Happened to Membrane-Bound Organelles?

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In summary, the membrane bound organelles present in the eukaryote that consumed a prokaryote may have been lost after undergoing secondary endosymbiosis. These cells are only known through molecular evidence and their structure remains unidentified. There is speculation that these pre-eukaryotes may have already possessed internal membranes, but this has not been confirmed. This theory is known as the endosymbiotic theory proposed by Lynn Margulis.
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Thejas15101998
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What happened to the membrane bound organelles that were present in the eukaryote that gulped the primary endosymbiont (that is, the eukaryote that gulped a prokaryote), after the secondary endosymbiosis.
 
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Its not clear these cells were, but here is a recent thread about some which might have been a close relative to it.
These cells are only known from their molecules, they have not been identified and details of their structure are not yet known.
There is speculation that these pre-eukaryotes may have already had some internal membranes, but they have not yet been seen.
 
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This is the endosymbiotic theory by Lynn Margulis.
 

1. What is endosymbiotic theory?

Endosymbiotic theory is a scientific explanation for the origin of eukaryotic cells. It proposes that mitochondria and chloroplasts, two membrane-bound organelles found in eukaryotic cells, were originally free-living prokaryotic cells that were engulfed by larger host cells. Over time, these prokaryotic cells evolved into the specialized organelles we see today.

2. How did membrane-bound organelles form?

According to endosymbiotic theory, the process of endosymbiosis occurred over millions of years. It is believed that a larger host cell engulfed a smaller prokaryotic cell, forming a symbiotic relationship. Over time, the smaller cell evolved into a specialized organelle within the host cell, resulting in the formation of membrane-bound organelles.

3. What evidence supports endosymbiotic theory?

There is a significant amount of evidence that supports endosymbiotic theory. This includes the similarities between mitochondria and chloroplasts and free-living prokaryotic cells, such as their size, shape, and DNA structure. Additionally, both organelles have their own DNA and can reproduce independently, similar to prokaryotic cells. The presence of endosymbiotic relationships in other organisms also supports the theory.

4. How does endosymbiotic theory explain the presence of mitochondria and chloroplasts in eukaryotic cells?

Endosymbiotic theory explains that mitochondria and chloroplasts were once free-living prokaryotic cells that were engulfed by larger host cells. These cells evolved over time to form the specialized organelles we see in eukaryotic cells today. This theory also explains the similarities between the functions and structures of mitochondria and chloroplasts and those of prokaryotic cells.

5. Are there any challenges to endosymbiotic theory?

While endosymbiotic theory is widely accepted, there are some challenges to the theory. One of the main challenges is the lack of a clear explanation for how the initial endosymbiotic event occurred. Additionally, some scientists argue that the similarities between mitochondria and chloroplasts and prokaryotic cells could be the result of convergent evolution rather than endosymbiosis. However, the overwhelming amount of evidence in support of endosymbiotic theory makes it the most widely accepted explanation for the origin of membrane-bound organelles in eukaryotic cells.

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