Mitochondria are large cell organelles in plant and animal cells. They convert chemical energy from food in the cell to usable energy using oxygen. This process is called oxidative phosphorylation, which takes place inside the mitochondria. Reactions of Krebs cycle produce a chemical, NADH (Nicotinamide Adenine Dinucleotide, reduced form), which is then used by enzymes present in the inner mitochondrial membrane to generate energy rich adenosine triphosphate (ATP) molecules. These molecules are utilized by the cells whenever energy is required. Therefore, mitochondria are also referred as power houses of the cell. Mitochondria are abundantly present in muscle and brain cells, and sperms to supply ATPs during demand for energy. Monitoring biosafety of pharmaceutical drugs, insecticides, and other bioactive molecules to mitochondria is necessary because some of them interact with the mitochondrial membrane or membrane proteins, thereby affecting the energy levels of cells or even induces mitochondrial-dependent apoptosis (programmed cell death)
