definition of mitochondria
Mitochondria: Structures located in the cell's cytoplasm outside the nucleus. Mitochondria are responsible for energy production. Each consists of two sets of membranes: a smooth, continuous outer coat and an inner membrane arranged in tubules or in folds that form plate-like double membranes (cristae).The mitochrondria are the principal energy source of the cell.itochondria are responsible for energy production. Each consists of two sets of membranes: a smooth, continuous outer coat and an inner membrane arranged in tubules or in folds that form plate-like double membranes (cristae). The mitochrondria are the principal energy source of the cell.