With most proteins, it has a secondary and tertiary structure.

The alpha helix and beta sheets are found at the Secondary level of protein folding.

It's when the protein is taking its shape.

Secondary structure

There are four types of protein structure. These include primary structure, secondary structure, tertiary structure, and quaternary structure. Primary structure is the amino acid sequence. Secondary structure is the shape of the molecule. Tertiary structure is the interaction between groups. Quaternary structure is the interactions between protein subunits.

Protein tertiary structure is 3-D. Secondary structure is 2-D or linear.

I. e. the linear a-a sequence is the secondary structure.

Amino-acid monomers comprise the primary structure.

The primary structure is a one or two dimensional structure, whereas the secondary structure is a three dimensional structure in which different parts of the protein molecule bend and twist due to the formation of hydrogen bonds between atoms. This makes the secondary structure shorter than the primary structure.