Here's why:

* Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles.

* E. coli is a bacterium, and bacteria are classic examples of prokaryotes. They are found in the intestines of humans and animals, and some strains are essential for digestion, while others can cause illness.

Other examples of prokaryotes include:

* Cyanobacteria (blue-green algae)

* Salmonella

* Staphylococcus

* Streptococcus