1. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.1 Chapter 19 Amino Acids and Proteins 19.1 Proteins and Amino Acids

2. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.2 Functions of Proteins  Proteins perform many different functions in the body.

3. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.3 Amino Acids Amino acids  are the building blocks of proteins  contain a carboxylic acid group and an amino group on the alpha (  ) carbon  are ionized in solution  each contain a different side group (R)

4. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.4 Examples of Amino Acids

5. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.5 Types of Amino Acids Amino acids are classified as  nonpolar with hydrocarbon side chains (hydrophobic)  polar (neutral) with polar or ionic side chains (hydrophilic)  polar (acidic) with acidic side chains (hydrophilic)  polar (basic) with –NH 2 side chains (hydrophilic) Nonpolar Polar (neutral) AcidicBasic

6. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.6 Nonpolar Amino Acids A nonpolar amino acid has an R group that is H, an alkyl group, or aromatic.

7. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.7 Polar (Neutral) Amino Acids A polar amino acid has an R group that is an alcohol, thiol, or amide.

8. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.8 Polar (Acidic) and Polar (Basic) Amino Acids An amino acid is  acidic with a carboxyl R group (COO – )  basic with an amino R group (NH 3 + )

9. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.9 Learning Check Identify each of the following as a polar (P) or nonpolar (NP) amino acid.

10. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.10 Solution Polar (P) Identify each of the following as a polar (P) or nonpolar (NP) amino acid. Nonpolar (NP)

11. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.11 Fischer Projections of Amino Acids Amino acids  are chiral except glycine, which has two H atoms attached to the alpha carbon atom  have Fischer projections that are stereoisomers  that are L isomers are used in proteins