Now, the type of Glibla protein we're going to focus on in this lecture is hemoglobin. And hemoglobin is the oxygen carrier inside our blood. So hemoglobin essentially picks up oxygen in the lungs and it moves the oxygen via the blood, the circulatory system into the cells and tissues of our body that need the oxygen to synthesize ATP molecule. And hemoglobin has quadnary structure. In fact, it is a tetromer. It consists of four individual polypeptide subunits.