Loss of _____ leads to a loss of protein function (denaturation).

• A. Primary Sequence
• B. Shape
• C. Mass
• D. Color

Answer: (B)

Proteins need a specific three-dimensional shape to function. Denaturation disrupts the noncovalent interactions that hold the folded structure together, unraveling secondary, tertiary, and sometimes quaternary structure. When the shape is lost, the active site or binding regions no longer have the correct geometry to interact with substrates or other molecules, so the protein can’t perform its job. The primary sequence—the actual order of amino acids—stays the same, serving as the blueprint, but without the proper folded shape the function is lost. Mass and color aren’t what determine activity in this context, so changing those wouldn’t explain a loss of function due to denaturation.