🧠 Summary Table: Protein Structure

Level	Description	Bond Type	Example	Analogy
Primary	Linear sequence of amino acids	Peptide bonds	Insulin	Beads on a string
Secondary	Coiling or folding of chain	Hydrogen bonds	Alpha helix, Beta sheet	Ribbon curl or paper fan
Tertiary	3D shape of chain	Hydrogen, ionic, disulfide	Enzymes	Yarn tangled into a ball
Quaternary	Two or more chains joined	Hydrogen, ionic, hydrophobic	Hemoglobin	Puzzle pieces joined