And so the nitrogen will also have a partial negative charge. And so we have this polarity that exists on these side chains. And so these are also polar, and they will be much more reactive than any of these hydrophobic side chains. So generally, our polar side chains are more reactive than the hydrophobic side chains. Finally, we have cysteine. Now, cysteine is not only polar, but it's also very special because is responsible for forming these very important bonds known as disulfide bonds or disulfide bridges.