And when you place the protein into an aqueous solution, it's the hydrophilic amino acids that will be found on the surface interacting with the polar water molecules, forming hydrogen bonds, while the hydrophobic amino acids will be found inside that protein in the core. So we're basically going to get the following diagram. So this is our protein. The protein core consists of a non polar section, while the surface of the protein consists of the blue section that is basically the hydrophilic section. The hydrophilic amino acids and these water molecules will form hydrogen bonds with those hydrophilic amino acids found on the surface of that protein molecule. Now, the extent to which a given protein is soluble in water basically depends on the number of hydrophilic amino acids that are found on the surface of that protein and generally on that protein.