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Unit 1 Study Guide – The Chemistry and Organization of Life

Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry

Key Concepts

  • Organization: Hierarchy from atoms → molecules → organelles → cells → tissues → organs → organisms → populations → communities → ecosystems → biosphere.

  • Information Flow: DNA as the genetic material; gene expression process.

  • Energy & Matter: Energy flow (one-way) vs. matter cycling in ecosystems.

  • Interactions: Feedback mechanisms regulate biological processes.

  • Evolution: Natural selection drives adaptation and diversity.

Scientific Inquiry

  • Inductive reasoning: Specific observations → general principles.

  • Deductive reasoning: General principles → specific predictions.

  • Hypothesis-based science: Must be testable and falsifiable.

Chapter 2: The Chemical Context of Life

Key Concepts

  • Elements & Compounds: 96% of life’s matter = C, H, O, N.

  • Atomic Structure: Protons (+), Neutrons (0), Electrons (-).

  • Chemical Bonds:

    • Covalent Bonds (strongest; share electrons).

    • Ionic Bonds (transfer electrons).

    • Hydrogen Bonds (weak but crucial in biology).

  • Chemical Reactions: Matter is rearranged, not created/destroyed.

Chapter 3: Water and Life

Key Properties of Water

  1. Cohesion & Adhesion – Water molecules stick together and to surfaces (e.g., plant transport).

  2. High Specific Heat – Stabilizes temperature.

  3. Expansion Upon Freezing – Ice is less dense than liquid water.

  4. Versatile Solvent – Dissolves many substances due to polarity.

Acids, Bases, and pH

  • pH <7 = Acidic, >7 = Basic, 7 = Neutral.

  • Buffers help maintain homeostasis (e.g., carbonic acid in blood).

Chapter 4: Carbon and Molecular Diversity

Key Concepts

  • Carbon's Versatility: Forms 4 covalent bonds, allowing complex molecules.

  • Organic Molecules: Backbone of life’s molecules.

  • Isomers: Molecules with same formula but different structures:

    • Structural: Different connectivity.

    • Cis-trans: Differ in spatial arrangement.

    • Enantiomers: Mirror images.

  • Functional Groups (e.g., Hydroxyl, Carbonyl, Carboxyl, Amino, Phosphate).

Chapter 5: The Structure & Function of Large Biological Molecules

Macromolecules

  1. Carbohydrates – Monosaccharides, disaccharides, polysaccharides (e.g., starch, glycogen, cellulose).

  2. Lipids – Hydrophobic, includes fats, phospholipids, steroids.

  3. Proteins – Made of amino acids, function depends on shape (4 levels of structure).

  4. Nucleic Acids – DNA/RNA, store and transmit genetic info.

Chapter 7: Membrane Structure and Function

Key Concepts

  • Fluid Mosaic Model: Membranes = phospholipid bilayer + proteins.

  • Transport Across Membranes:

    • Passive Transport (no energy): Diffusion, Osmosis, Facilitated Diffusion.

    • Active Transport (requires ATP): Moves against concentration gradient.

    • Bulk Transport: Endocytosis (into cell), Exocytosis (out of cell).