NEET 2026
- Exam
- NEET
- Year
- 2026
- Subject
- Chemistry
- Chapter
- Chapter
NEET 2026 · Chemistry · Chapter
When milk is converted into curd, the proteins present in it...
When milk is converted into curd, the proteins present in it undergo denaturation due to the decrease in pH caused by lactic acid. Which of the following correctly describes the structural changes occurring in the protein during this process?
Options
- AThe primary structure is destroyed while the secondary and tertiary structures remain intact.
- BThe secondary and tertiary structures are destroyed, but the primary structure remains intact.
- CThe peptide bonds are cleaved, breaking the protein chain into free amino acids.
- DThe protein chain undergoes further coiling to form a more complex quaternary structure.
Correct answer
B. The secondary and tertiary structures are destroyed, but the primary structure remains intact.
Step-by-step solution
During the conversion of milk into curd, the lactic acid produced by bacteria lowers the pH, leading to the denaturation of milk proteins (such as casein).
Denaturation is a process in which proteins lose their secondary and tertiary structures due to the disruption of non-covalent interactions (like hydrogen bonds, hydrophobic interactions, and disulfide bridges) caused by changes in temperature, pH, or chemical environment.
However, the primary structure, which consists of the sequence of amino acids held together by strong covalent peptide bonds, remains intact and is not destroyed during denaturation.
Answer: The secondary and tertiary structures are destroyed, but the primary structure remains intact.
Denaturation is a process in which proteins lose their secondary and tertiary structures due to the disruption of non-covalent interactions (like hydrogen bonds, hydrophobic interactions, and disulfide bridges) caused by changes in temperature, pH, or chemical environment.
However, the primary structure, which consists of the sequence of amino acids held together by strong covalent peptide bonds, remains intact and is not destroyed during denaturation.
Answer: The secondary and tertiary structures are destroyed, but the primary structure remains intact.