And that single polypeptide subunit contains one heme group. And that means that myoglobin can only bind a single diatomic oxygen molecule. On top of that, because we don't have more than two polypeptide subunits within myoglobin to actually interact with one another and create Cooperativity, that implies that myoglobin will not display Cooperativity and so it will not create a sigmoidal curve. And the shape of our oxygen myoglobin dissociation curve is given by the red curve. So once again, the y axis is percent saturation of myoglobin and the X axis is the partial pressure of diatomic oxygen given in millimeters of mercury. Now, the next question is what exactly determines the difference between these two curves?