BIOL 408 Exam Study Guide PDF

Chapter 10: Biomembrane Structure I. The Fluid Mosaic Model of Biomembranes ​ Plasma Membrane (PM): ○​ Composed of lipid bilayer, proteins, and carbohydrates. ○​ Functions as a semi-permeable barrier, regulating the movement of substances. ○​ Exhibits fluidity due...

Chapter 10: Biomembrane Structure I. The Fluid Mosaic Model of Biomembranes ​ Plasma Membrane (PM): ○​ Composed of lipid bilayer, proteins, and carbohydrates. ○​ Functions as a semi-permeable barrier, regulating the movement of substances. ○​ Exhibits fluidity due to lateral movement of lipids and proteins. ​ Types of Membrane Proteins: ○​ Integral (Transmembrane) Proteins: Span the bilayer. ○​ Peripheral Proteins: Attach via non-covalent interactions. ○​ Lipid-Anchored Proteins: Covalently bonded to lipids (e.g., GPI anchors). II. Composition of Biomembranes ​ Lipid Bilayer: ○​ Hydrophilic head groups face outward, hydrophobic tails face inward. ○​ Cholesterol modulates fluidity and stability. ​ Membrane Lipids: ○​ Phospholipids: Glycerophospholipids (e.g., phosphatidylcholine, phosphatidylserine). ○​ Sphingolipids: Sphingomyelin, glycolipids, ceramides. ○​ Sterols: Cholesterol in animals, phytosterols in plants. ​ Membrane Asymmetry: ○​ Different lipid compositions in cytosolic vs. extracellular leaflets. ○​ Flipases, Floppases, and Scramblases regulate lipid distribution. III. Membrane Properties and Dynamics ​ Self-sealing and fusion properties: Enables vesicle formation, endocytosis, and exocytosis. ​ Lateral diffusion: Movement of lipids/proteins within the membrane. ​ Phase transition (gel → fluid state): Temperature-dependent changes in membrane fluidity. ​ Lipid Rafts: ○​ Rich in cholesterol and sphingolipids. ○​ Specialized for signaling and trafficking. IV. Transport Across the Membrane ​ Passive Transport: ○​ Simple diffusion (O₂, CO₂, small lipophilic molecules).  ○​ Facilitated diffusion (via channels or transporters). ​ Active Transport: ○​ Requires ATP (e.g., Na+/K+ ATPase, Ca²+ ATPase). ​ Endocytosis & Exocytosis: ○​ Endocytosis: Phagocytosis (large particles), pinocytosis (fluids), receptor-mediated. ○​ Exocytosis: Secretion of substances (e.g., neurotransmitters). Chapter 11: Transmembrane Transport of Ions and Small Molecules I. Overview of Membrane Transport Mechanisms ​ Pumps (Primary Active Transport): ATP-powered, move molecules against gradients. ​ Channels: Allow specific ion passage down electrochemical gradients. ​ Transporters (Carriers): Conformational change-mediated transport. II. Types of Transporters ​ Uniporters: Transport a single molecule down its gradient (e.g., GLUT1 for glucose). ​ Symporters: Move two molecules in the same direction (e.g., Na+/glucose symporter). ​ Antiporters: Move two molecules in opposite directions (e.g., Na+/H+ exchanger). III. ATP-Powered Transport Proteins ​ P-Class Pumps: ○​ Na+/K+ ATPase (pumps 3 Na+ out and 2 K+ in per cycle). ○​ Ca²+ ATPase (sarcoplasmic reticulum, muscle contraction). ​ V-Class Pumps: ○​ Acidify organelles (lysosomes, endosomes) by pumping H+ inside. ​ F-Class Pumps: ○​ ATP synthase in mitochondria and chloroplasts (proton gradient-driven ATP production). ​ ABC Transporters: ○​ Multidrug resistance (MDR1), CFTR (cystic fibrosis chloride channel). IV. Ion Channels & Action Potentials ​ Resting membrane potential (~ -70 mV): Set by Na+/K+ ATPase and K+ leak channels. ​ Voltage-Gated Ion Channels:  1.​ Open/close in response to voltage changes (e.g., Na+, K+, Ca²+ channels). ​ Action Potential: 1.​ Depolarization: Na+ channels open, Na+ influx. 2.​ Repolarization: K+ channels open, K+ efflux. 3.​ Refractory period: Na+ channels temporarily inactivated. Chapter 12: Cellular Energetics I. Overview of Cellular Respiration ​ Aerobic Respiration: O₂ is final electron acceptor in the electron transport chain. ​ Anaerobic Respiration: Alternative electron acceptors (e.g., sulfate, nitrate). ​ Overall Equation:​ C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + 30-32 ATP II. Stages of Glucose Oxidation 1.​ Glycolysis (Cytoplasm): ○​ Glucose → 2 Pyruvate + 2 ATP + 2 NADH 2.​ Pyruvate Oxidation (Mitochondrial Matrix): ○​ Pyruvate → Acetyl-CoA + NADH + CO₂ 3.​ Citric Acid Cycle (TCA Cycle): ○​ Produces NADH, FADH₂, and ATP/GTP. 4.​ Electron Transport Chain & Oxidative Phosphorylation: ○​ Generates proton gradient, driving ATP synthesis via ATP Synthase. III. Lipid and Protein Metabolism ​ Fatty Acid Oxidation (Beta-Oxidation): ○​ Acyl-CoA → Acetyl-CoA + NADH + FADH₂ ​ Protein Catabolism: ○​ Amino acids are deaminated, entering TCA cycle. IV. Photosynthesis 1.​ Light-Dependent Reactions (Thylakoid Membrane): ○​ Photosystem II (P680) splits H₂O, producing O₂ and protons. ○​ Photosystem I (P700) reduces NADP+ to NADPH. 2.​ Calvin Cycle (Stroma of Chloroplasts): ○​ Fixes CO₂ into glyceraldehyde-3-phosphate (G3P).