JEE Chemistry 2024 Question with Solution

Given: Egg white protein is boiled and coagulates.

Find: Which level of protein structure remains intact after boiling.

Boiling causes denaturation of proteins. Denaturation disrupts the secondary, tertiary, and quaternary structures because these depend mainly on hydrogen bonding and other interactions responsible for higher-order folding.

The primary structure is the linear sequence of amino acids connected by peptide bonds. These covalent bonds are not broken during ordinary boiling.

Therefore, after coagulation of egg white on boiling, the structure that remains intact is Primary.

The correct option is A.

Given: Proteins have primary, secondary, tertiary, and quaternary structures.

Find: Which one survives heat-induced coagulation of egg white.

1. Primary structure: sequence of amino acids in the polypeptide chain. This remains intact because boiling does not break peptide bonds.
2. Secondary structure: includes alpha-helices and beta-sheets stabilized mainly by hydrogen bonds. Heat disrupts these bonds.
3. Tertiary structure: the three-dimensional folding of a protein. Heat disturbs the interactions maintaining this folding.
4. Quaternary structure: association between multiple polypeptide chains. This is also disrupted during denaturation.

Thus, coagulation on boiling destroys the higher-order structures but not the amino acid sequence itself.

Hence, the correct answer is Primary, so the correct option is A.