Living By Chemistry SECOND EDITION Unit 2: SMELLS Molecular Structure and Properties

Lesson 48: Protein Origami Amino Acids and Proteins

ChemCatalyst The mirror-image isomers of carvone are shown. 1. Explain how the receptor sites for D-carvone and L-carvone might be different from each other. 2. Sketch receptor sites for D-carvone and L-carvone. Assume that the polar side (the side with the oxygen atom) attaches to the receptor site.

Key Question What is a receptor site made of?

You will be able to: explain that protein molecules are chains of amino acid molecules understand that the smell receptor sites are protein chains folded to form a receptor of a specific shape explain the “handedness” of a smell receptor site

Prepare for the Activity Work in groups of four. Amino acid: A molecule with a carboxyl functional group and an amine functional group. Protein: A large molecule consisting of amino acids bonded together.

Discussion Notes Amino acids are molecules with a carboxyl group, COOH, and an amine group, NH2. Amino acids can link together to form long chains called proteins. Protein molecules fold to form pockets because of attractions between the R groups on different amino acids in the chain.

Wrap Up What is a receptor site made of? Amino acids are molecules with a carboxyl group, COOH, and an amine group, NH2. Amino acids all have mirror-image isomers. Only left-handed amino acid molecules function in the human body. The carboxyl group from one amino acid can link with the amine group of another amino acid forming a peptide bond.

Wrap Up (cont.) Proteins are long chains of amino acids linked together. Protein molecules can fold to form smell receptor sites.

Check-In Name two concepts from the Smells Unit that were used today to help you understand proteins.