Final answer:
The level of structure in a protein described by the statement is the secondary structure, specifically the alpha-helix. Certain proteins coil into a helix, stabilized by intrachain hydrogen bonding. Examples include a-keratins found in hair and wool.
Step-by-step explanation:
The level of structure in a protein that is described by the statement 'The chain of amino acids coils into a helix' is the secondary structure. According to Linus Pauling and Robert Corey, certain proteins or portions of proteins twist into a spiral or a helix, which is known as a right-handed alpha-helix. This helix is stabilized by intrachain hydrogen bonding between amino acids. Examples of proteins with helical structure include a-keratins found in hair and wool. Other proteins may have different secondary structures or have little to no helical structure.