Final answer:
The strongest lines of evidence for the endosymbiotic hypothesis of eukaryotic origin include similarities in mitochondrial DNA, the presence of double cell layers in chloroplasts, and variation in eukaryotic genes.
Step-by-step explanation:
The endosymbiotic hypothesis proposes that eukaryotes evolved from a fusion of different types of cells. The strongest lines of evidence to support this hypothesis include:
- Similarities in mitochondrial DNA: Mitochondria, which are organelles involved in energy production, have their own DNA that is separate from the DNA in the cell nucleus. The DNA in mitochondria is similar to the DNA found in bacteria, suggesting that mitochondria were originally bacteria that were incorporated into eukaryotic cells through endosymbiosis.
- Presence of double cell layers in chloroplasts: Chloroplasts are organelles involved in photosynthesis. They have a double membrane structure similar to certain types of bacteria, indicating that chloroplasts were also acquired through endosymbiosis.
- Variation in eukaryotic genes: Some genes in eukaryotes resemble those found in Archaea, while others resemble those found in Bacteria. This variation supports the idea that eukaryotes originated from the fusion of different types of cells.