And that means it's hydrophobic. It will not easily dissolve in our blood plasma. So how exactly do we solve this problem? 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.