Bonds in Protein Tertiary and Quaternary Structures

Steps:

• Identify bonds in tertiary structure: disulfide bridges (strong covalent) and non-covalent interactions like hydrogen and ionic bonds (weak).
• Identify bonds in quaternary structure: disulfide bridges between subunits (strong) and non-covalent interactions (weak).
• Interpret choices as two bonds for tertiary followed by two for quaternary.
• Select option matching strong-weak for both structures.

Why B is correct:

• B (strong weak strong weak) aligns with protein biochemistry, where both structures feature strong disulfide bonds and weak non-covalent bonds for stability.

Why the others are wrong:

• A: Falsely assigns only weak bonds to quaternary structure, ignoring disulfides.
• C: Falsely assigns only weak bonds to tertiary structure, omitting disulfides.
• D: Falsely assigns only weak bonds to tertiary and mostly weak to quaternary.

Final answer: B