Function of Mitochondrial Cristae. Before we can explain the functioning of the crista (plural = cristae), we need to revisit what a mitochondrion does. The mitochondrion is the cellular organelle where cellular respiration takes place.Cellular respiration is the process that creates chemical energy in the form of ATP from simple food molecules.ristae are folds of the inner mitochondrial membrane. The electron transport chain and chemiosmosis takes place on this membrane as part of cellular respiration to create ATP and can be seen in the diagram: