What does the term “cysteine bond” refer to in hair chemistry?

The term “cysteine bond” refers to a specific type of bond in the hair's structure that plays a crucial role in chemical texturizing services, which include processes like perms or relaxing treatments. Cysteine bonds are formed by the amino acid cysteine, and they are classified as disulfide bonds. These bonds contribute significantly to the strength and shape of the hair.

During chemical texturizing services, these disulfide bonds are broken using reducing agents. This breaking is essential because it allows the hair's structure to be reshaped. After the hair has been reshaped—often when neutralizers are applied—these bonds reform, essentially "locking in" the new shape or texture of the hair. This dynamic process of breaking and reforming is key to achieving the desired results in chemical treatments.

In contrast, the other options do not accurately represent the nature of cysteine bonds. They do not enhance color vibrancy, remain unaffected by chemical treatments, or exist solely in curly hair. Instead, the focus is on their involvement in the transformation of hair texture during chemical services.