Answer:
Hydrophobic part
Explanation:
A protein is made up of amino acids. Some amino acids such as serine and threonine are polar and hydrophilic in nature as they have polar side chains. The other amino acids such as alanine and proline are non-polar as they have nonpolar side chains.
The polar amino acids of a polypeptide chain are folded towards the inside of the protein to avoid any interaction with the surrounding watery medium. On the other hand, the polar and charged amino acids are oriented towards the surface of a folded protein. This arrangement makes the proteins stable.
