Here's why:

* Prokaryotes are organisms that lack a nucleus and other membrane-bound organelles. They have a simpler structure and include bacteria and archaea.

* Eukaryotes have a nucleus and other membrane-bound organelles. They are more complex and include animals, plants, fungi, and protists (like amoebas).

Amoebas have a nucleus, a cell membrane, cytoplasm, and other organelles. They are classified as protists, which are a diverse group of mostly single-celled eukaryotic organisms.