Coenzyme Q10 is a component of the electron transport chain and participates in aerobic cellular respiration, generating energy in the form of ATP. In its reduced form, it acts as an antioxidant. Coenzyme Q2 is a precursor of coenzyme Q10 that has 2, rather than 10, isoprenoid units on the ubiquinone base. It can act as an electron acceptor for bacterial Complex I. In mammalian cells, exogenous coenzyme Q2 prevents the production of reactive oxygen species associated with Complex I activity. Forms of coenzyme Q with shorter isoprenoid chains, including coenzyme Q2, induce p53-dependent apoptosis in human B-cell acute lymphoblastoid leukemia BALL-1 cells.