When O 2 is not available to the cell, then the cell must convert to an anaerobic means of metabolism called fermentation. There are various types of fermentation but we will primarily focus on alcoholic fermentation and lactic acid fermentation. These types of electron transfers are called Redox reactions. The electron carriers that are important in cellular respiration are NADH and FADH 2 . Glycolysis a series of redox reactions resulting in the breakdown of one glucose into two pyruvic acid molecules.
Glycolysis occurs in the cytoplasm of the cell.
Throughout the series of reactions, CO2 is released and several molecules of NADH or FADH 2 are reduced. These play a critical role in the next stage of respiration, the electron transport chain. These chemical reactions occur in the matrix of the mitochondria. This is where the majority of ATP molecules are synthesized for cellular respiration. Importantly, the mitochondrial membrane is involved with this series of redox reactions.