Mitochondria are membrane-bound organelles found in the cytoplasm of all eukaryotic cells.
The function of mitochondria in both plant and animal cells is to generate cellular energy through the production of adenosine triphosphate (ATP) as part of the Krebs circuit.
ATP is used by all living cells to produce energy.
Mitochondria resemble bacterial cells but have their own DNA.
Thus, mitochondria is not a cell but it is a cell organelle.