Mitochondria are organelles found in most eukaryotic cells (https://en.wikipedia.org/wiki/Eukaryote), including human cells. They are often called the "powerhouses" of the cell because they generate most of the cellular energy in the form of adenosine triphosphate (ATP). Mitochondria have their own DNA and can replicate independently of the cell's nucleus. They are involved in many metabolic pathways. https://en.wikipedia.org/wiki/Metabolic_pathway.

Joseph Pizzorno, ND, Editor in Chief 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684129/#:~:text=This%20function%20is%20so%20important,from%201000%20to%202500%20mitochondria.