24.3 Amino Acids and Polymers Quiz

Amino Acids Overview

• Amino acids are essential nitrogen-containing molecules in living organisms.
• The 20 common amino acids are crucial for various biological processes.

Structure of Amino Acids

• Comprised of a central carbon atom bonded to a carboxyl group, an amino group, a hydrogen atom, and a unique R-group side chain.

Properties of Amino Acids

• Differences in amino acid properties arise from varied R-group side chains.
• Side chains can be nonpolar (aliphatic/aromatic), polar, acidic, or basic.

Peptide Bonds

• Peptide bonds form between the carboxyl group of one amino acid and the amino group of another.
• Each bond results from a condensation reaction, generating a water molecule.

Writing Peptide Formulas

• Peptide formulas are conventionally written with the free amino group on the left and the free carboxyl group on the right.

Amino Acid Sequence

• The sequence of amino acids in a peptide is expressed using three-letter abbreviations (e.g., Asp—Glu—Gly).
• Peptides can be extended indefinitely through condensation polymerization.

Polypeptides and Proteins

• A peptide chain with over ten amino acids is termed a polypeptide.
• Chains exceeding 100 amino acids are classified as proteins, which are vital biomolecules found in skin, hair, nails, and muscles.

Sources of Amino Acids

• Some amino acids are synthesized by the body, while others must be obtained from protein-rich foods such as beans and brown rice.

Protein Structure

• The 3D structure of proteins is influenced by interactions among amino acids within the peptide chains.
• Hydrogen bonds between folded chains contribute to maintaining protein shape.

Helix Structure

• Some peptide chains coil into a regular spiral known as a helix, as observed in myoglobin, which stores oxygen in muscle tissue.

Pleated Sheet Structure

• Peptide chains can also form a pleated sheet configuration by arranging side by side.

Enzymes as Catalysts

• Enzymes, a subset of proteins, serve as biological catalysts, speeding up chemical reactions by lowering activation energy without being consumed in the process.

Fun Fact

• Urease was the first enzyme isolated (by James B. Sumner in 1926) and is involved in breaking down urea, a component of urine.