Here's a breakdown:

* Amino acids: These are the building blocks of proteins. Each amino acid has a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (-H), and a side chain (R group).

* Peptide bonds: Amino acids join together through peptide bonds, which are formed between the carboxyl group of one amino acid and the amino group of another.

* Polypeptide chain: A chain of amino acids linked by peptide bonds is called a polypeptide chain.

* Protein: A protein is a complex, three-dimensional structure made up of one or more polypeptide chains. The specific sequence of amino acids in a protein determines its unique shape and function.

So, in essence, proteins are formed when amino acids link together in a specific sequence through peptide bonds.