We are learning about proteins and their structure, but one thing is confusing me.

Question

At what structural point is something considered a protein? Is a protein formed after two amino acids synthesis, or is a protein the whole structure (all four levels) put together?

I would think you would need all four structural levels to form a protein, but my teacher refers to the first structure as a protein molecule.

Thanks for the clarification.

Answer 1

They need all three levels of structure (i.e., primary, secondary, and tertiary structure.) Anything less than 20 amino acids is rarely consider a protein, and not all proteins have quanternary structure. Only proteins that are composed of two or more polypeptide chains are considered to have quanternary structure.

Answer 2

Thanks! Great answer. :)