I use a book to practice GRE Biology and one of those questions that I am confused of it. I hope somebody could help me. Thanks!
The denaturing of a protein by heat or radiation is caused by the destruction of which structures? A. Secondary and tertiary
B. Secondary and quarternary
C. Secondary, tertiary and quarternary
D. Tertiary and quarternary
The correct answer is A and C is my choice, but I can’t understand why the answer is A. I think the quarternary structure is changed by the denaturation of the secondary and tertiary structures.
Secondary structure is usually a product of bond angles, which aren’t strongly affected by the radiations mentioned. As other have said, quaternary isn’t always there, but it still seems a better part of a double answer than secondary.
I guess I’m not wild about the possible choices, either. I would argue for A as being correct only because it is possible to disrupt quaternary structure without unfolding or denaturing the subunits. But it is almost certainly true that if you disrupt secondary and tertiary structures, you will per force destroy any quaternary structure as well.