Protein Structure in Enzymes and Antibodies

Steps:

• Statement 1 is correct: Hydrogen bonds stabilize secondary and tertiary structures, enabling proper folding and function in enzymes (active sites) and antibodies (binding sites).
• Statement 2 is incorrect: Hydrophobic R-groups cluster inward to avoid water, promoting globular folding, but proteins adopt compact globular shapes, not precisely spherical ones, due to multiple interactions.
• Statement 3 is correct: Tertiary structure determines the 3D shape critical for enzyme catalysis and antibody-antigen recognition.
• Thus, only statements 1 and 3 apply to both enzyme and antibody molecules.

Why C is correct:

• C selects statements 1 and 3, aligning with the definition of protein folding where hydrogen bonds and tertiary structure are essential for biological function per biochemistry principles.

Why the others are wrong:

• A includes incorrect statement 2 on spherical shape.
• B omits correct statement 3 on tertiary structure.
• D omits correct statement 1 on hydrogen bonds.

Final answer: C