How does symbiogenesis explain reproduction of organelles along with the cell?
I'm not sure about all organelles but mitochondria and chloroplasts are commonly used examples of independent devision in eukaryotic cells. They have independent DNA that forms separate mitotic spindles during division. Similar mechanisms likely existed for other organelles originally but the genetic material may have eventually been combined with the nuclear DNA for simplicity. This is a very simplified explanation but I think addresses the basic question.