Question

The first true prokaryote cells were formed from

Answer 1

Protobionts.

Prokaryotes, which were the first living organisms, probably evolved from protobionts. Eukaryotes formed later, from endosymbiosis of multiple prokaryote ancestors.

The earliest prokaryotes absorbed energy from extracellular reactions to power the formation of ATP within the cell. These chemiautotrophic cells probably used carbon dioxide as the carbon source and the energy of ATP to construct larger and more complex molecules. Another theory, called the heterotroph hypothesis, suggests that the aquatic environment was full of organic molecules, including ATP, which were then absorbed into the cell for cellular functions. The first heterotrophs could have survived easily on the supposed soup of organic molecules in their consumptive environment. However, at some point the heterotrophs would inevitably exhaust their food supply and the autotrophic system would replace the heterotrophs and become established as the dominant life-form. In both cases, the presence of enzymes was necessary, and they originated from spontaneous combinations of organic molecules.