A protein found in a biological system with a unique three-dimensional structure and biological activity is subjected to a significant change in pH, causing it to lose its biological activity. What is the term used for the protein in its original active state, and which of its structural levels remains intact after the pH change?

Step-by-step solution

According to NCERT, a protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a native protein is subjected to a physical change (like temperature) or a chemical change (like a change in pH), it undergoes denaturation. During denaturation, the protein loses its biological activity because the secondary and tertiary structures are destroyed (globules unfold and helices uncoil). However, the primary structure (the specific sequence of ami