We add one more carbon atom compared to this one here. And in this particular case, we take this methyl group and we place it onto this carbon. So these two amino acids are more hydrophobic than Valene, and valine is, in turn, more hydrophobic than aline, because the more carbon H atoms we have, the more hydrophobicity found within that particular amino acid. So that's exactly why valine is more electronegative than Alanine and so forth. Now, what distinguishes Leucine from isolucine? Well, it's the fact that this carbon here contains this methyl group, and that makes this carbon a chiral carbon.