Question

Митохондрии и хлоропласты более миллиарда лет назад были самостоятельными организмами. Приведите факты, свидетельствующие об этом:

Answer 1

Согласно симбиогенетической теории пластиды, как и митохондрии, произошли в результате «захвата» древней цианобактерии предшественником эукариотической «хозяйской» клетки. При этом внешняя мембрана пластид соответствует плазматической мембране хозяйской клетки, межмембранное пространство — внешней среде, внутренняя мембрана пластид — мембране цианобактерии, а строма пластид — цитоплазме цианобактерии. Наличие трёх (эвгленовые и динофлагелляты) или четырёх (золотистые, бурые, желто-зеленые, диатомовые водоросли) мембран считается результатом двух- и трёхкратного эндосимбиоза соответственно. 
У митохондрии есть днк,это доказывает то, что она была независимым организмом

Answer 2

Mitochondria and Chloroplasts as Independent Organisms

There is evidence to suggest that mitochondria and chloroplasts were once independent organisms over a billion years ago. Here are some facts that support this idea:

1. Endosymbiotic Theory: The endosymbiotic theory proposes that mitochondria and chloroplasts were once free-living bacteria that were engulfed by ancestral eukaryotic cells. This theory suggests that these organelles have their own DNA and replicate independently within the cell.

2. Similarities to Bacteria: Mitochondria and chloroplasts share several characteristics with bacteria. They have their own DNA, ribosomes, and can produce some of their own proteins. Additionally, they have a double membrane structure, similar to that of bacteria.

3. Genetic Evidence: The DNA of mitochondria and chloroplasts is similar to that of bacteria. The genes found in these organelles are more closely related to bacterial genes than to the genes found in the nucleus of the host cell. This suggests that mitochondria and chloroplasts have a bacterial origin.

4. Ability to Replicate: Mitochondria and chloroplasts have the ability to replicate independently within the cell. They have their own machinery for DNA replication and protein synthesis, which is similar to that of bacteria.

5. Evolutionary Relationships: Phylogenetic analysis has shown that mitochondria are most closely related to a group of bacteria called alpha-proteobacteria, while chloroplasts are most closely related to cyanobacteria. This further supports the idea that these organelles were once independent organisms.

It is important to note that while these facts support the idea that mitochondria and chloroplasts were once independent organisms, the exact details of how this symbiotic relationship originated are still the subject of ongoing research and investigation.