California Cosmetology Written ExamChemical Texture ServicesEasy
A cosmetology instructor explains that salt bonds in the hair's cortex are formed by the attraction between positively and negatively charged amino acid side chains. Which statement about salt bonds is accurate?
- AThey are physical bonds that can be broken by strong alkaline or acidic pH changes
- BThey are weaker than hydrogen bonds and are unaffected by water or pH
- CThey form only during the neutralization phase of a permanent wave
- DThey are the strongest bonds in the hair and require thioglycolate to break
Show answer & explanationAnswer & explanation
Correct answer: A. They are physical bonds that can be broken by strong alkaline or acidic pH changes
Salt bonds are physical (ionic) side bonds formed by attraction of positive and negative charges along the polypeptide chain; they are broken by pH extremes (very high or very low pH), unlike hydrogen bonds which are broken by water/heat.
Why the other options are wrong
- B. Salt bonds are stronger than hydrogen bonds but ARE affected by pH changes.
- C. Salt bonds exist naturally in hair and are not created during neutralization.
- D. Disulfide bonds, not salt bonds, are broken by thioglycolate reduction.
Salt Bond
A weak physical side bond in the cortex formed by attraction between positive and negative electrical charges on adjacent protein chains.
- Broken by strong alkaline or acidic pH
- About 1/3 as strong as hydrogen bonds
- Reform when hair returns to normal pH
Memory trick: Salt bonds are like magnets—pH extremes flip the charge and break them apart.