H&A 2

LEARNING OBJECTIVES

  • Understand macromolecule synthesis

  • Describe types and functions of proteins

  • Discuss amino acids' relationship with proteins

  • Describe nucleic acids' structure and types

  • Explain DNA and RNA structure and roles

  • Discuss carbohydrate roles and classifications

  • Describe four major types of lipids and phospholipids' roles

FOUR MAJOR CLASSES OF MACROMOLECULES

  1. Nucleic Acids: DNA, RNA

  2. Carbohydrates: Sugars

  3. Proteins

  4. Lipids: Fats

  • Organic molecules containing carbon and may also contain H, O, N, and other elements.

PROTEINS

  • Composed of 20 amino acids with unique side chains.

  • Formed by polymerization of amino acids.

  • Structure levels: Primary, Secondary, Tertiary, Quaternary.

MACROMOLECULE SYNTHESIS

  • Macromolecules: Giant molecules formed by joining smaller units (monomers) via condensation (dehydration) reactions.

  • Hydrolysis is the reverse reaction, breaking polymers apart by adding water.

  • Polymerization = requires energy, Hydrolysis = energy release.

  • Anabolic (synthesis) + Catabolic (breakdown) = Metabolism.

AMINO ACIDS

  • Composed of central carbon, hydrogen atom, amino group (NH2), carboxyl group (COOH), and variable side chain (R group).

  • Side chain groups: 1) Charged (acidic, basic), 2) Uncharged polar, 3) Nonpolar.

  • Essential amino acids must be supplied in diet.

PEPTIDE BONDS

  • Form between carboxyl group of one amino acid and amino group of another.

  • Peptide bond creates a stable backbone for proteins.

  • Directionality: N-terminus to C-terminus.

PROTEIN STRUCTURE

  1. Primary: Unique sequence of amino acids.

  2. Secondary: Formation of α-helices and β-pleated sheets via hydrogen bonds.

  3. Tertiary: 3D shape from interactions between R-groups.

  4. Quaternary: Assembly of multiple polypeptide subunits.

FOLDING AND FUNCTION

  • Proper folding is crucial for protein function, often assisted by molecular chaperones.

  • Alterations in pH/temperature can lead to denaturation.

PROTEIN FUNCTIONS

  • Catalysis, defense, movement, signaling, structure, transport.

  • Enzymes: Specific proteins that catalyze reactions by binding substrates at active sites.