Mitochondria are unable to survive outside of eukaryotic cells. If they originated from ancestral prokaryotes, as proposed by the endosymbiotic theory, then why can’t they survive independently?
Mitochondria are indeed believed to have originated from ancestral prokaryotes through endosymbiosis. According to the endosymbiotic theory, an ancestral prokaryote was engulfed by a host cell and formed a symbiotic relationship that eventually led to the development of mitochondria. However, over time, mitochondria have become completely dependent on eukaryotic cells and are unable to survive independently.
There are a few reasons why mitochondria cannot survive outside of eukaryotic cells:
1. Loss of Genetic Material: As an endosymbiotic organism, mitochondria have lost a significant portion of their original genetic material during the course of evolution. Many genes from the ancestral prokaryote have been transferred to the host cell's genome. This loss of genes has made mitochondria reliant on the host cell to provide essential proteins and products.
2. Loss of Protein Production Machinery: Mitochondria have also lost the ability to produce many of their own proteins. Genes that were once involved in protein synthesis have been transferred to the host cell's nucleus. As a result, mitochondria rely on the host cell to synthesize the necessary proteins for their function.
3. Dependence on Host Cell for Resources: Mitochondria require a constant supply of nutrients and substances like oxygen to carry out oxidative phosphorylation, a process essential for energy production in eukaryotic cells. These resources are provided by the host cell, making mitochondria dependent on the host cell's metabolic processes.
4. Interdependence: Mitochondria and host cells have developed a mutualistic relationship, where both entities rely on each other for survival. The host cell provides the necessary resources for mitochondrial function, while mitochondria supply the cell with energy in the form of ATP. This interdependence has become essential for both mitochondria and eukaryotic cells to function properly.
In summary, mitochondria have lost their independence due to the extensive transfer of genetic material to the host cell, loss of protein production machinery, dependence on the host cell for resources, and the establishment of an interdependent relationship with eukaryotic cells. As a result, mitochondria have become an integral part of eukaryotic cells and cannot survive outside of them.