The cell-organelle Mitochondria, on it's inner surface of the cristae membranes i.e, towards mitochondrial matrix side, contains large number of knob or globular shaped particles with a conspicuous stalk like structure. Such globular particulate are called Racker particles which are also known as F1 particles. They act as ATP synthetases and are uniformly spaced at 10 nm apart. Their number in each mitochondria ranges from 100 to 1000.