Protein Structure Features in Enzymes and Antibodies

Steps:

• Statement 1 is correct: Hydrogen bonds stabilize secondary and tertiary structures in proteins like enzymes and antibodies.
• Statement 2 is incorrect: Hydrophilic R-groups point outward to interact with water, while hydrophobic ones cluster inside; proteins fold into specific 3D shapes, not necessarily spherical.
• Statement 3 is correct: Tertiary structure determines the active site in enzymes and binding site in antibodies, enabling function.
• Valid statements are 1 and 3, corresponding to option C.

Why C is correct:

• C selects statements 1 and 3, aligning with the definition of protein folding where hydrogen bonds maintain structure and tertiary conformation dictates biological activity per biochemistry principles.

Why the others are wrong:

• A includes incorrect statement 2 on R-group positioning.
• B omits correct statement 3 on tertiary structure's role.
• D includes incorrect statement 2 and omits statement 1 on hydrogen bonds.

Final answer: C