This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
[{'content': 'Which of the following structure is not affected in protein denaturation? \nSelect and explain. \nA. Primary structure, B. Secondary structure, C. Tertiary structure, D. Quaternary structure', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) Primary structureRef: Harper's Biochemistry, 30lh ed. pg. 26-29, 618-19 |PROTEIN DENATURATION* In quaternary structure denaturation, protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted.* Primary structure, such as the sequence of amino acids held together by covalent peptide bonds, is not disrupted by denaturation.* In secondary structure denaturation proteins adopt a random coil as they lose all regular repeating patterns such as alpha-helices and beta-pleated sheets, and configuration.* Tertiary structure denaturation involves the disruption of:1. Covalent interactions between amino acid side- chains (such as disulfide bridges between cysteine groups)2. Non-covalent dipole-dipole interactions between polar amino acid side-chains (and the surrounding solvent)3. Van der Waals (induced dipole) interactions between nonpolar amino acid side-chains.", 'role': 'assistant'}]