Previously, we discussed 15 of the 20 amino acids that make up the proteins found in the human body. So we spoke about the eight hydrophobic amino acids. We spoke about the five polar but uncharged amino acids, and we also discussed the two special cases, proline and glycine. Now let's discuss the five remaining amino acids. And the special thing about these these five remaining amino acids is they all contain a full charge on their side chain groups at the normal physiological PH. And that's exactly what makes them very highly hydrophilic, because they have that full charge.