And once the two three BPG molecules are inside the capillaries, they enter the red blood cells where we have the hemoglobin molecule. So to see what we mean, let's take a look at the following diagram. So, these are the exercising cells that have a relatively high rate of metabolism found within our tissue. Now, when we produce an excess amount of two three BPG, some of these molecules leave the cell and enter our matrix. Now, what exactly does a two three BPG molecule actually look like? Well, it looks something like this.