Final answer:
The three forces that stabilize protein tertiary structure—hydrophobic interactions, ionic bonding, and hydrogen bonding—all involve the side chains and are generally weaker than covalent bonds. However, disulfide linkages, also important for tertiary structure, are covalent and stronger. The correct answer is therefore (e) Both (a) and (c).
Step-by-step explanation:
Tertiary Protein Structure Stabilization
The three main forces that stabilize protein tertiary structure share common characteristics: (a) They involve the side chains of amino acids within the protein. (b) They interact with the water molecules surrounding the protein, as hydrophilic side chains often interact with water to help dissolve the protein. (c) These forces are generally weaker than covalent bonds, which are the strongest type of chemical bond.
However, the tertiary structure of proteins does include some covalent bonding, such as disulfide bonds (bridges) that form between cysteine amino acids of the polypeptide. These covalent bonds between the sulfhydryl groups result from oxidation and are much stronger compared to other non-covalent interactions in the protein structure. So, while non-covalent interactions are weaker than covalent bonds, the vast number of these interactions cumulatively contributes significantly to the protein's stability.
Based on the information provided, the correct answer to the question 'What do the three main forces that stabilize protein tertiary structure have in common?' is (e) Both (a) and (c).