I think the answer is DNA
Protists are eukaryotes and bacteria are prokaryotes
They are found in the body
The answer is flagella.
Flagella are tail-like structures which allow some unicellular organisms to move. Although their primary function is in locomotion, they can also serve as sensory organelles that are sensitive to chemicals or temperature of the environment. They can be found in all three domains - bacteria, archaea, and eukaryota:
- Bacterial flagella have a rotary motor at the base of each filament turning clockwise or counterclockwise
- Archaeal flagella look like bacterial flagella.
- Eukaryotic flagella are structurally complex cellular projections.
