Which statement describes how hair protein chains interact to contribute to structure?

• A. Salt bonds connect proteins between chains
• B. Hydrogen bonds form permanent covalent links
• C. Disulfide bonds do not influence strength
• D. Bonding of protein chains to other protein chains

Answer: (D)

Hair gains its structure from keratin protein chains that cross-link with one another. When protein chains bond to other protein chains, they form a network that provides strength, shape, and resilience. This cross-linking is how the hair’s fibers stay connected and hold their form. Different bonds contribute to this network: disulfide bonds are strong covalent links that greatly influence strength and permanence, while salt and hydrogen bonds also help hold the shape though they’re weaker and more easily altered by moisture or heat. In short, the bonding of protein chains to other protein chains captures the essential idea of how hair structure is built.