The theory of endosymbiosis states that 1.5bn years ago, some early eukaryotes (the ancestor cells of animals and plants) engulfed bacterial cells and kept them prisoner inside their cells. They did this so they could harvest the sugars that the bacterial cells were producing. The bacterial cells used light to produce sugars from carbon dioxide and water. Eventually, these engulfed bacteria became which type of organelles?
Answers
Answer: They became Chloroplasts
What happened to make eukaryotes so complicated? And where did these organelles that look like batteries originate from?
We believe we know a portion of the solution. Multiple cells joining together to form a single eukaryotic cell might have developed into eukaryotic cells. They developed what are known as symbiotic partnerships. Endosymbiotic hypothesis is the theory that explains how this may have happened. An endosymbiont is a type of creature that lives within another. All eukaryotic cells, including your own, are animals built out of other species' components.
Organelles such as the mitochondrion and chloroplast were formerly free-living cells. They were prokaryotes that had found their way into other cells (host cells). They may have joined the other cell by being eaten (a process known as phagocytosis), or they could have been parasites.
The inner cell survived rather than being digested or killed by the host cell, and the two of them thrived together. It's similar to a landlord and a tenant situation. The organelle pays rent by producing energy that the host cell may utilize, and the organelle offers a nice, safe place to dwell. This occurred a long time ago, and the organelle and host cell have developed together through time. One can no longer exist without the other. They now work as a single organism, but if we look closely, we can see traces of the organelles' former life as free-living cells.