Well, basically, our red blood cells carry a special type of transporter protein of carrier protein known as hemoglobin. And what hemoglobin does is it picks up these oxygen molecules and it carries and it protects those oxygen molecules from the hydrophilic environment. So basically, hemoglobin consists of four polypeptide subunits. So this is what the hemoglobin, the hemoglobin protein, actually looks like. We have subunit one shown in green, subunit two shown in purple, subunit three shown in brown and subunit four shown in orange. Now, notice that within each one of these subunits, we have a hydrophobic section right inside.