They don't have organelles. Earth's atmosphere wasn't like today's atmosphere. 3.5 Billion years ago, the atmosphere of Earth was mostly Nitrogen , Carbon Dioxide and Methane.
Cyanobacteria
Somewhere between 2.5 and 3.5 billion years ago, one of these microbial species, evolved a new ability: Photosynthesis.
Photosynthesis gave those bacteria a huge advantage over other species. They could produce their own energy from and endless supply of raw ingredients, so they multiplied and their populations increased. Then they polluted the atmosphere with oxygen.
Death to all organisms on Earth!!!!!!!!!!!!!
But while the cyanobacteria were producing faster than it could be absorbed, it caused a big problem!
Geologist called this the "Oxygen Catastrophe
The planet was basically a giant snowball
Then the Huronian Glaciation happened.
Imagine this as Earth.
Which is the ancestor of plant cells and cyanobacteria became a part of this bacteria which are chloroplasts.
By the way, hundreds of million of years ago, a prehistoric microbe swallowed a cyanobacterium whole in a process called endosymbiosis.
Cyanobacteria are still around in almost every environment on Earth
Sukurta daugiau nei 30 milijonų siužetinių lentelių