Now, what happens if we can't produce these hydroxyproline groups? Well, basically, a condition in humans of a disease known as Scurvy is essentially this inability of Collagen to basically produce and modify its own proline molecules in the following way. So, in Scurvy, the body has a deficiency of vitamin C, and vitamin C is needed to basically modify and convert the proline molecules into hydroxyproline. And so, because we can't modify these amino acids in this way, the structure of collagen basically is destabilized. And what that means is it decreases the strength of our tissue. Now let's move on to carboxyl groups.