Answer:
The correct answer is - on the surface.
Explanation:
Proteins are made up of long chains called polypeptide chains made up of amino acid residues linked together. These amino acid residues could be hydrophobic or hydrophilic in nature. Hydrophilic is the nature of water-loving whereas hydrophobic is that tries to avoid water.
So, if a protein placed inside the water the hydrophilic amino acids will be present on the surface of the protein, and hydrophobic amino acids present inside of the protein structure.
