Lecture Notes: The Chemical Building Blocks of Life

Introduction

• Lecture recorded due to public holidays and scheduling conflicts.
• Topic: Chapter 3 - The Chemical Building Blocks of Life.

Unifying Concept of Biology

• Despite diversity among organisms, chemistry unites all life.
• Macromolecules are key chemical building blocks.

Basic Chemistry Recap

• Elements form molecules and compounds via bonds.
• These form larger structures called macromolecules.
• Four main macromolecules: proteins, lipids, nucleic acids, carbohydrates (not fats).

Organic Molecules and Carbon

• Made primarily of carbon.
• Carbon's 4 valence electrons allow it to form 4 bonds.
• Carbon skeletons are the backbone of macromolecules.
• Carbon and hydrogen form non-polar bonds due to similar electronegativity.

Functional Groups

• Addition of O, N, S, P introduces polarity.
• Common functional groups:
  • Hydroxyl (OH)
  • Carbonyl (CO)
  • Carboxyl (COOH)
  • Amino (NH2)
  • Sulfhydryl (SH)
  • Phosphate
  • Methyl
• Functional groups alter molecular properties.

Isomers

• Molecules with same formula but different structures.
  • Structural Isomers: Different carbon skeletons.
  • Stereoisomers: Different spatial arrangement.
  • Enantiomers: Mirror image isomers.
  • Chiral carbons: Different groups on each carbon atom.

Macromolecule Basics

• Polymers are large molecules made of repeating monomers.
• Dehydration synthesis forms polymers; hydrolysis breaks them.

Carbohydrates

• Defined by 1:2:1 ratio of carbon, hydrogen, oxygen.
• Functions: Energy storage and structural support.
• Types of Carbohydrates:
  • Monosaccharides: Simple sugars; glucose, fructose, galactose.
  • Disaccharides: Two monosaccharides joined; sucrose, lactose, maltose.
  • Polysaccharides:
    • Energy storage: Starch (plants), glycogen (animals).
    • Structural: Cellulose (plants).

Nucleic Acids

• DNA and RNA are polymers of nucleotides.
• Nucleotide components: Sugar, phosphate, nitrogenous base.
• DNA: Double-stranded, stores genetic info.
• RNA: Single-stranded, various functions including protein synthesis.

Proteins

• Functions: Enzymes, defense, transport, support, motion, regulation, storage.
• Composed of amino acids, each with a variable R group.
• Structures:
  • Primary: Sequence of amino acids.
  • Secondary: Alpha helices and beta sheets.
  • Tertiary: 3D folding of secondary structures.
  • Quaternary: Interaction of multiple polypeptides.
• Chaperones assist in proper protein folding.
• Denaturation can occur with changes in temperature, pH, ionic concentration.

Lipids

• Not polymers; diverse forms (fats, oils, waxes, vitamins).
• Hydrophobic due to non-polar CH bonds.
• Types of Lipids:
  • Triglycerides: Glycerol + 3 fatty acids.
  • Saturated vs. Unsaturated Fats:
    • Saturated: No double bonds, solid at room temperature.
    • Unsaturated: Double bonds, liquid at room temperature.
  • Phospholipids: Glycerol + 2 fatty acids + phosphate.
    • Form cell membranes, amphipathic nature (polar head, non-polar tails).

Conclusion

• Understanding these building blocks is essential for biology.
• Reach out for help if needed.