Both bacteria and amoeba are unicellular organisms. Bacteria are considered to be prokaryotes, whereas amoebas are considered to be eukaryotes. How will you justify this reasoning? Though both are unicellular, bacteria possess a well-defined nucleus without anucleolus. Amoebas possesses a nucleus with a nucleolus, but no nuclear membrane. Though both are unicellular, bacteria possess a well-defined nucleus and all essential cell organelles, whereas amoebas do not possess a nucleus or cell organelles, except ribosomes. Though both are unicellular, bacteria doesn’t possess a nucleus or cell organelles, except ribosomes, whereas amoebas possess a well-defined nucleus and all essential cell organelles.