Milady Cosmetology Practice Exam

Which type of bonds are responsible for the overall strength of the hair structure?

1. Covalent Bonds

2. Hydrophobic Bonds

3. Disulfide Bonds

4. Peptide Bonds

The correct answer is: Disulfide Bonds

Disulfide bonds are key to the overall strength of the hair structure due to their unique chemical properties. They are a type of covalent bond formed between the sulfur atoms of two cysteine amino acids, which are building blocks of proteins found in hair. These bonds are strong and contribute significantly to the hair's resilience and structural integrity. In hair, the presence of disulfide bonds creates a stable and durable framework, which helps maintain its shape and strength. This is particularly important when considering chemical processes like perming or relaxing hair, which involve breaking and reforming these bonds to alter the hair's texture. While covalent bonds and peptide bonds are also critical in the overall structure of hair, disulfide bonds play a more specific role in providing strength. Hydrophobic bonds, on the other hand, relate to the interaction of nonpolar substances with water and do not contribute directly to the structural strength of hair like disulfide bonds do.