Chapter 2 - The Chemistry of Biology - Critical Thinking Questions - Bloom's Levels 3, 4, and 5: Apply, Analyze, and Evaluate - Page 53: 8

Secondary levels of protein structures are formed by hydrogen bonding, forming two types of structures, i.e., alpha helix and beta strands. On the other hand tertiary levels of protein structures are formed by disulfide bonds or salt bridges and three dimensional structures are formed by polypeptide chains.

See answer.