AI Tutor
When you crack an egg into a hot skillet, the clear, runny liquid turns solid and rubbery white in seconds. That dramatic transformation happens because heat unravels the intricate 3D shapes of proteins.
Every protein begins as a sequence of small building blocks called amino acids, each containing a central carbon, an amino group, a carboxyl group, and a unique R group (side chain).
How do these individual amino acids link together to form a functioning molecular machine?

Primary Structure: The Sequence

Primary structure is the unique linear sequence of amino acids joined end-to-end by covalent peptide bonds.
What happens when this long chain of amino acids begins to twist and fold along its backbone?

Secondary Structure: Helices and Sheets

In 1951, chemist Linus Pauling discovered that regular hydrogen bonds between backbone atoms force the chain into repetitive local patterns.
These local patterns form either a delicate spiral called an alpha helix or a flat, accordion-like fold called a beta-pleated sheet.
Helices and sheets are still mostly flat or linear shapes. How does the protein collapse into a compact, three-dimensional tool?