California Cosmetology Written ExamChemical Texture ServicesEasy
A cosmetologist explains to a client that the bonds broken by a permanent wave's reducing lotion and reformed by the neutralizer are located within the cortex and hold the hair's overall strength and shape. Which bond is this?
- AHydrogen bond
- BPeptide bond
- CSalt bond
- DDisulfide bond
Show answer & explanationAnswer & explanation
Correct answer: D. Disulfide bond
Disulfide bonds are strong, permanent chemical (sulfur) bonds between cystine amino acids in the cortex. They are the only bonds broken by chemical texture reducing agents and reformed by oxidation (neutralizing).
Why the other options are wrong
- A. Hydrogen bonds are weak, temporary, broken by water/heat only.
- B. Peptide bonds link amino acids end-to-end and form the polypeptide chain itself.
- C. Salt bonds are weak physical bonds broken by pH change.
Disulfide Bond
A strong chemical (sulfur-to-sulfur) side bond between cystine amino acids in the hair cortex that is broken by reducing agents and reformed by oxidation.
- Only bond type broken by permanent wave/relaxer chemicals
- Reformed via oxidation (neutralizer) or lanthionization (hydroxide relaxers)
- Gives hair its strong, permanent structural shape
Memory trick: 'Disulfide = Diamond-strong Do-over bond'