A hemoglobin molecule consists of four polypeptide chains:two a globin chains (shown in green and blue)and two B globin chains (shown in yellow and orange).Each globin chain contains a heme (shown in red).A hemoglobin molecule consists of four polypeptide chains: two a globin chains (shown in green and blue) and two b globin chains (shown in yellow and orange). Each globin chain contains a heme (shown in red)