Origin of Eukaryotic Cells by Endosymbiosis
A range of evidence supports a model called endosymbiosis, which proposes that mitochondria and chloroplasts in plants were originally small prokaryotes that began living in larger cells. This theory was first postulated by biologist Lynn Margulis in the 1960s and her original hypothesis proposed that mitochondria were derived from aerobic bacteria, whereas chloroplasts were derived from photosynthetic bacteria or cyanobacteria.
The prokaryotic ancestors of mitochondria and chloroplasts probably gained entry into the host cell as undigested prey or internal parasites that later came to enter into a mutually beneficial relationship with the host. As host and endosymbiont became more interdependent, the two eventually became intergrated into a single organism.
There is supporting evidence for the theory of endosymbiosis. First, The DNA of mitochondria and chloroplasts is similar to that found in bacteria. Also, both mitochondria and chloroplasts are surrounded by two membranes: the inner membrane is like that of a prokaryotic cell membrane whereas the outer membrane is more like the eukaryotic plasma membrane. Thirdly, mitochondria are about the same size as bacteria.
Origin of Eukaryotic Cells by Endosymbiosis
A range of evidence supports a model called endosymbiosis, which proposes that mitochondria and chloroplasts in plants were originally small prokaryotes that began living in larger cells. This theory was first postulated by biologist Lynn Margulis in the 1960s and her original hypothesis proposed that mitochondria were derived from aerobic bacteria, whereas chloroplasts were derived from photosynthetic bacteria or cyanobacteria.
The prokaryotic ancestors of mitochondria and chloroplasts probably gained entry into the host cell as undigested prey or internal parasites that later came to enter into a mutually beneficial relationship with the host. As host and endosymbiont became more interdependent, the two eventually became intergrated into a single organism.
There is supporting evidence for the theory of endosymbiosis. First, The DNA of mitochondria and chloroplasts is similar to that found in bacteria. Also, both mitochondria and chloroplasts are surrounded by two membranes: the inner membrane is like that of a prokaryotic cell membrane whereas the outer membrane is more like the eukaryotic plasma membrane. Thirdly, mitochondria are about the same size as bacteria.
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