Comprehensive Study Guide: BIOL 1406

1. Cell Structure & Theory

Cell Theory (3 Principles)

  1. All living organisms are composed of one or more cells.

  2. The cell is the basic unit of life.

  3. All cells arise from pre-existing cells.

Cell Size & Diffusion Constraints

  • Cells rely on diffusion to transport nutrients & waste.

  • Smaller cells = higher surface area-to-volume ratio (better efficiency).

  • Larger cells compensate with multiple nuclei or elongated shapes.

Common Features in All Cells

  • Genetic material (DNA/RNA)

  • Cytoplasm (fluid-filled interior)

  • Plasma membrane (selective barrier)

  • Ribosomes (protein synthesis)

2. Prokaryotic vs. Eukaryotic Cells

Prokaryotes (Bacteria & Archaea)

  • No nucleus, DNA in nucleoid region

  • No membrane-bound organelles

  • Cell wall (peptidoglycan in bacteria, unique lipids in archaea)

  • Shapes: Coccus (spherical), Bacillus (rod), Spiral

  • Features: Capsule (protection), Flagella (movement), Fimbriae (attachment), Endospores (dormant state)

Eukaryotes (Plants, Animals, Fungi, Protists)

  • Larger (~10-100 μm)

  • Nucleus (contains DNA)

  • Membrane-bound organelles: ER, Golgi, Mitochondria, Lysosomes, etc.

  • Cytoskeleton: Actin filaments, Microtubules, Intermediate filaments

  • Plant Cells: Have cell wall (cellulose) and chloroplasts

  • Animal Cells: Have centrioles & lysosomes

3. Biological Membranes & Transport

Fluid Mosaic Model

  • Phospholipid bilayer: Hydrophilic heads & Hydrophobic tails

  • Membrane proteins: Transport, Receptors, Enzymes, Cell identity

  • Cholesterol: Affects membrane fluidity

Transport Mechanisms

Passive Transport (No Energy Required)

  • Simple Diffusion: Movement from high → low concentration

  • Facilitated Diffusion: Uses channel/carrier proteins

  • Osmosis: Water moves toward higher solute concentration

Active Transport (Requires ATP)

  • Na+/K+ Pump: Pumps 3 Na+ out, 2 K+ in

  • Coupled Transport: Uses concentration gradient to move substances

Bulk Transport

  • Endocytosis (into the cell): Phagocytosis (solids), Pinocytosis (liquids)

  • Exocytosis (out of the cell): Secretion of large molecules

4. Macromolecules & Biochemistry

Carbohydrates

  • Monosaccharides: Glucose, Fructose

  • Disaccharides: Sucrose, Lactose

  • Polysaccharides: Starch (plants), Glycogen (animals), Cellulose (cell walls)

Proteins

  • Monomer: Amino acids

  • Bond: Peptide bond

  • Structure:

    1. Primary – Amino acid sequence

    2. Secondary – Alpha helices & Beta sheets

    3. Tertiary – 3D folding (R-group interactions)

    4. Quaternary – Multiple polypeptide chains

Lipids

  • Fats (Triglycerides): Energy storage

  • Phospholipids: Cell membrane structure

  • Steroids: Cholesterol, Hormones

Nucleic Acids

  • DNA & RNA: Genetic information storage & transfer

  • Nucleotides: Sugar + Phosphate + Nitrogenous Base (A, T/U, C, G)

5. Enzyme Function & Metabolism

Enzymes (Biological Catalysts)

  • Lower activation energy of reactions

  • Substrate binds to Active Site (Lock & Key or Induced Fit Model)

  • Can be affected by:

    • Temperature & pH

    • Competitive inhibitors (block active site)

    • Allosteric inhibitors (change enzyme shape)

Feedback Inhibition

  • Final product inhibits an earlier enzyme to prevent excess production

6. Cellular Respiration

ATP: Energy Currency of the Cell

  • ATP → ADP + P (Exergonic, Releases Energy)

  • ADP + P → ATP (Endergonic, Requires Energy)

Stages of Cellular Respiration

  1. Glycolysis (Cytoplasm)

    • Glucose → 2 Pyruvate + 2 ATP + 2 NADH

    • Anaerobic (Does not require oxygen)

  2. Krebs Cycle (Mitochondrial Matrix)

    • Pyruvate → CO₂ + NADH + FADH₂ + 2 ATP

  3. Electron Transport Chain (Inner Mitochondrial Membrane)

    • NADH & FADH₂ donate electrons → H⁺ pumped out

    • Oxygen = final electron acceptor → forms H₂O

    • ATP Synthase produces ~34 ATP via Chemiosmosis

Aerobic vs. Anaerobic Respiration

  • Aerobic: Requires oxygen, produces ~36 ATP

  • Anaerobic: No oxygen, produces lactic acid or ethanol

7. Gibbs Free Energy, Redox Reactions, & pH

Gibbs Free Energy (ΔG)

  • ΔG = ΔG(products) - ΔG(reactants)

  • Exergonic (ΔG < 0): Releases energy, Spontaneous

  • Endergonic (ΔG > 0): Requires energy, Non-Spontaneous

Redox Reactions (LEO goes GER)

  • Lose Electrons = Oxidation (energy loss)

  • Gain Electrons = Reduction (energy gain)

  • Electron carriers (NADH, FADH₂): Key in respiration.

pH & Buffers

  • pH scale (0-14): Acids (0-6), Neutral (7), Bases (8-14).

  • Buffers: Stabilize pH (e.g., blood bicarbonate system).

Key Takeaways for Review

✔ Know the key principles, don’t stress over details. ✔ Understand major differences (Prokaryotes vs. Eukaryotes, Aerobic vs. Anaerobic Respiration). ✔ Master transport mechanisms & enzyme function. ✔ Recognize energy flow (ATP, Gibbs Free Energy, Redox). ✔ pH balance & buffers keep biological systems stable.