National Occupational Competency Testing Institute (NOCTI) Cosmetology Practice Exam

The correct answer is that cystine disulfide bonds are broken during the processing of a chemical permanent wave. Cysteine is an amino acid that contains sulfur, and when two cysteine molecules are linked by a sulfur-sulfur bond, this forms a disulfide bond. These disulfide bonds play a crucial role in the hair's structure, providing strength and shape to the hair strands.

During the process of a chemical permanent wave, the hair is exposed to a reducing agent, which breaks these disulfide bonds. Once these bonds are broken, the hair can be reshaped around curlers or rods. After the desired shape is achieved, an oxidizing agent is then applied to reform the disulfide bonds in the new shape, effectively locking in the curl or wave.

While hydrogen bonds, salt bonds, and peptide bonds are also important in hair structure and stability, they are not specifically broken during the perming process. Hydrogen bonds are relatively weak and can be temporarily affected by moisture and heat. Salt bonds, which are also weaker interactions involving the hair's pH level, can be disrupted by changes in pH but are not specifically targeted in permanent waving. Peptide bonds form the basic structure of proteins and are not