Medical Genetics If the sickled cells had changed shape, perhaps it was because the hemoglobin had been altered in some way, making it clump and stick to one another, as antigens stick to antibodies. Pauling had already shown that hemoglobin changed shape slightly when it was oxygenatedMedical Genetics If the sickled cells had changed shape, perhaps it was because the hemoglobin had been altered in some way, making it clump and stick to one another, as antigens stick to antibodies. Pauling had already shown that hemoglobin changed shape slightly when it was oxygenated