The first complex cells had genes from a complex mix of species

These cells already had complex interiors, with internal protein trackways traversed by motor proteins that move cargo within the cell. There were structures (lysosomes and peroxisomes) meant to digest proteins within the cells, and all the basics of eukaryotic metabolism, DNA replication, and RNA production. One of the big features that was absent were sets of genes used to determine when a cell should divide and managing the events that need to take place for that to happen. …