Proteins are large, complex molecules that play a vital role in many biological processes. They are made up of long chains of amino acids linked together by peptide bonds.

Here are some key points to remember:

* Amino acids: The building blocks of proteins. There are 20 different types of amino acids commonly found in proteins.

* Peptide bonds: The chemical bonds that connect amino acids together.

* Polypeptide chain: A long chain of amino acids linked by peptide bonds.

* Protein: A complex molecule made up of one or more polypeptide chains.

The specific sequence of amino acids in a protein determines its unique three-dimensional structure and its function. Proteins have a wide range of functions in the body, including:

* Enzymes: Catalyze biochemical reactions.

* Structural components: Provide support and shape to cells and tissues.

* Hormones: Act as chemical messengers.

* Antibodies: Fight infections.

* Transport proteins: Carry molecules across cell membranes.