What are the 4 different protein types and shapes?

Proteins can be categorized into four main types based on their structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids, while secondary structures include alpha helices and beta sheets formed by hydrogen bonding. The tertiary structure represents the three-dimensional shape of a single polypeptide chain, and quaternary structure involves the assembly of multiple polypeptide chains into a functional protein complex. Each level of structure is crucial for the protein's overall function.