1.3 Hemoglobin is a much more intricate and sentient (sensitive)molecule than is myoglobin. 1.3.1 The oxygen-binding (dissociation)curve of hemoglobin is sigmoidal and that of myoglobin is perboric 1.3.2 Myoglobin has a higher affinity for O2, evolved for O, storage 1.3.3 Hemoglobin releases O, efficiently at low oxygen level tissues(evolved for O2 delivery), myoglobin does not 1.3. 4 Oxvgen binding of hemoglobin shows positive cooperativity. The binding of O2(the ligand) at one heme facilitates the binding of o2 at the other hemes on the same tetramer(vice versa, unloading of oxygen at one heme facilitates the unloading of oxygen at the others). (Negative cooperativity refers to a decrease of activity.1.3 Hemoglobin is a much more intricate and sentient (sensitive) molecule than is myoglobin. 1.3.1 The oxygen-binding (dissociation) curve of hemoglobin is sigmoidal and that of myoglobin is hyperbolic. 1.3.2 Myoglobin has a higher affinity for O2 , evolved for O2 storage. 1.3.3 Hemoglobin releases O2 efficiently at low oxygen level tissues (evolved for O2 delivery), myoglobin does not. 1.3.4 Oxygen binding of hemoglobin shows positive cooperativity. The binding of O2 (the ligand) at one heme facilitates the binding of O2 at the other hemes on the same tetramer (vice versa, unloading of oxygen at one heme facilitates the unloading of oxygen at the others). (Negative cooperativity refers to a decrease of activity.)