[Campbell Biology P.112] Based on the information provided, why do "permanent" treatments in... | Practice Question

Based on the information provided, why do "permanent" treatments in hair salons involve breaking and reforming cross-links formed by specific chemical groups?

  • A: To alter the hair's shape (straightness or curliness) by modifying the protein structure, specifically by breaking and re-forming sulfhydryl cross-links.
  • B: To add a negative charge to the hair, which helps in absorbing hair dye more effectively.
  • C: To convert hair proteins into a different type of acid, making the hair softer and more manageable.
  • D: To enable the hair to pick up H+ from the surrounding solution, thus neutralizing any alkaline residues.

Explanation

The Sulfhydryl group -SH forms "cross-links" that stabilize protein structure, including hair proteins. "Permanent" treatments in hair salons work by breaking these cross-links, reshaping the hair, and then re-forming them to maintain the new shape, as described in the table for the Sulfhydryl group.