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Chapter 19 Amino Acids and Proteins. 19.1 Proteins and Amino Acids. Functions of Proteins. Proteins perform many different functions in the body. Amino Acids. Amino acids are the building blocks of proteins contain a carboxylic acid group and an amino group on the alpha ( ) carbon
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Chapter 19 Amino Acids and Proteins 19.1Proteins and Amino Acids
Functions of Proteins • Proteins perform many different functions in the body.
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)
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–NH2 side chains (hydrophilic) Nonpolar Polar (neutral) Acidic Basic
Nonpolar Amino Acids A nonpolar amino acid has an R group that is H, an alkyl group, or aromatic.
Polar (Neutral) Amino Acids A polar amino acid has an R group that is an alcohol, thiol, or amide.
Polar (Acidic) and Polar (Basic) Amino Acids An amino acid is • acidic with a carboxyl R group (COO–) • basic with an amino R group (NH3+)
Learning Check Identify each of the following as a polar (P) or nonpolar (NP) amino acid.
Solution Identify each of the following as a polar (P) or nonpolar (NP) amino acid. Nonpolar (NP) Polar (P)
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