And what that means is, at certain PH values, these ionizable sidechain groups will be able to exchange hydrogen atoms. They can donate and accept hydrogen atoms. And that gives them the ability not only to participate in acidbased reaction actions, but to also form ionic bonds. Because if the side chain groups can form ions, the ions have full charges, and those charges can participate in forming ionic bonds with other macromolecules. So that's exactly what makes these seven amino acids reactive. And that's what gives them the ability to participate in a variety of different types of biological reactions that take place inside our bodies.