How Eukaryotic Cells Became Complex

Eukaryotic cells became complex through a debated evolutionary path that likely involved endosymbiosis. The most accepted model is the endosymbiont theory, which explains how organelles such as mitochondria and chloroplasts may have entered an ancestral cell. Other ideas include the nucleus-first hypothesis, the mitochondria...

The first eukaryotic cell originated from a primitive prokaryotic cell, which had its genetic material freely bundled in the cytoplasm.

These cells were surrounded by a plasma membrane but lacked any membrane-bound organelles inside.

As the cell evolved, the plasma membrane invaginated and pinched off, giving rise to membrane-enclo...