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).