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Chapter 3 Structure and Function of Cells Suggested Lecture Presentation Robert J. Sullivan Marist College Copyright © 2009 Pearson Education, Inc. Cells Are Classified by Internal Organization Eukaryotes have Plasma membrane Nucleus: information center Cytoplasm: fluid within membrane Organelles: structures with specialized functions Prokaryotes have No nucleus No true organelles Copyright © 2009 Pearson Education, Inc. Cell Structure Reflects Cell Function Muscle cells Contain numerous organelles providing energy needed for muscle contraction Nerve cells Long and thin to carry impulses over distance Small size is efficient Copyright © 2009 Pearson Education, Inc. 1 The Plasma Membrane Extracellular environment Receptor protein Channel protein (always open) Gated channel protein (closed position) Cytoskeleton Phospholipid filaments Cytoplasm Carbohydrate groups Lipid Transport Glycoprotein bilayer protein Cholesterol Copyright © 2009 Pearson Education, Inc. Figure 3.5 Structural Features of the Plasma Membrane Lipid bilayer Phospholipids: polar head and nonpolar tail Cholesterol: makes membrane a bit more g rigid Proteins: provide means of transportation through membrane Carbohydrates: recognition patterns for cells and organisms Copyright © 2009 Pearson Education, Inc. Diffusion: Passive Transport Through Membrane Passive transport No energy required Diffusion Movement from area of high concentration to low Copyright © 2009 Pearson Education, Inc. Figure 3.6 2 Osmosis: Diffusion of Water Osmosis: net diffusion of water across a semipermeable membrane Copyright © 2009 Pearson Education, Inc. Figure 3.7 Three Forms of Passive Transport Passive transport is powered by the concentration gradient. In the cell it occurs as Diffusion through lipid layer Diffusion Diff i th through h protein t i channels h l Facilitated transport Transport or carrier proteins in the membrane assist in moving molecules across the membrane, down the concentration gradient, without expending energy Copyright © 2009 Pearson Education, Inc. Active Transport Active transport requires energy to move substances from an area of l lower concentration i to an area of higher concentration. Copyright © 2009 Pearson Education, Inc. Figure 3.9 3 Endocytosis and Exocytosis Move Materials in Bulk Endocytosis moves material into cell Exocytosis moves material out of cell Copyright © 2009 Pearson Education, Inc. Figure 3.10a–b Receptor Proteins in Active Transport Receptor proteins Span membrane Receptor sites Bind specific molecules Copyright © 2009 Pearson Education, Inc. Figure 3.11 Active Transport: The Sodium–Potassium Pump Sodium–potassium pump expels unwanted ions, keeps needed ones, and maintains cell volume ATP is used to expel three sodium ions for every two potassium ions brought into the cell IIncrease cellll volume l = iincrease water t iin cytoplasm by decreasing pumping and allowing more sodium inside cell Decrease cell volume = less water in cytoplasm by increasing pumping and expelling more sodium ions Copyright © 2009 Pearson Education, Inc. 4 Active Transport: The Sodium–Potassium Pump Copyright © 2009 Pearson Education, Inc. Figure 3.12a Active Transport: The Sodium–Potassium Pump Copyright © 2009 Pearson Education, Inc. Figure 3.12b Variations in Tonicity Isotonic Extracellular and intracellular ionic concentration equal Hypotonic yp Extracellular ionic concentration less than intracellular Hypertonic Extracellular ionic concentration more than intracellular Copyright © 2009 Pearson Education, Inc. 5 Tonicity Figure 3.13a Copyright © 2009 Pearson Education, Inc. Internal Structures of an Animal Cell Cytosol Semifluid gel material inside the cell Peroxisome Destroys cellular toxic waste Nucleus Information center for the cell. Contains DNA Centrioles Microtubular structures involved in cell division Cytoskeleton Structural framework of the cell Smooth endoplasmic reticulum Primary site of macromolecule synthesis other than proteins Rough endoplasmic reticulum Primary site of protein synthesis by ribosomes Golgi apparatus Refines, packages, and ships macromolecular products Secretory vesicle Membrane-bound shipping container Ribosomes Site of protein synthesis Mitochondrion Produces energy for the cell Plasma membrane Controls movement of materials into and out of cell Lysosome Digests damaged organelles and cellular debris Copyright © 2009 Pearson Education, Inc. Figure 3.14 Structure and Function of the Nucleus Functions Contains the genetic information of the cell Controls the cell Structural features Double-layered nuclear membrane Nuclear pores Chromosomes/chromatin Nucleolus Copyright © 2009 Pearson Education, Inc. 6 Structure and Function of the Nucleus Copyright © 2009 Pearson Education, Inc. Figure 3.15 Endoplasmic Reticulum (ER) and Ribosomes Ribosomes Used in protein assembly Free and membrane bound Endoplasmic reticulum (ER) Packages the proteins Smooth ER: no ribosomes, lipid synthesis Rough ER: has ribosomes, protein manufacture Copyright © 2009 Pearson Education, Inc. Endoplasmic Reticulum (ER) and Ribosomes Copyright © 2009 Pearson Education, Inc. Figure 3.16 7 Golgi Apparatus Receives substances from ER, refines and packages them Smooth ER Golgi apparatus Vesicle Lysosome Secretory vesicle Plasma membrane Figure 3.17 (1 of 2) Copyright © 2009 Pearson Education, Inc. Vesicles Ship and Store Cellular Products Harmless waste Alcohol Vesicles Ship and store cellular products Secretory membranemembrane bound spheres Examples: secretory, endocytic, peroxisomes, lysosomes Peroxisome Golgi apparatus Cell toxic waste Lysosome Residual body Bacterium Plasma membrane Copyright © 2009 Pearson Education, Inc. Figure 3.18 Mitochondria: Provide Energy to the Cell Double membrane Inner membrane contains enzymes that break down foods Liberated energy is used to create ATP Copyright © 2009 Pearson Education, Inc. Figure 3.19a 8 Energy Storage Fat Triglycerides Long-term energy storage in animals Glycogen Carbohydrate storage Short-term energy storage in animals Copyright © 2009 Pearson Education, Inc. Cytoskeleton Supports the Cell Microtubules Microfilaments Copyright © 2009 Pearson Education, Inc. Figure 3.20 Cell Structures for Support and Movement: Cilia, Flagella, Centrioles Cilia and flagella Used in movement 9 + 2 microtubule arrangement Centrioles Used in cell division Copyright © 2009 Pearson Education, Inc. Figure 3.20 9 Cells Use and Transform Matter and Energy: Two Basic Metabolic Pathways Anabolism Requires enzymes Making/assembling large molecules May require energy (ATP) Used in building up cell components Used in storing energy Copyright © 2009 Pearson Education, Inc. Cells Use and Transform Matter and Energy: Two Basic Metabolic Pathways Catabolism Requires enzymes Breakdown of molecules May release energy Used in breaking down nutrients and recycling cell components Used to access energy storage Copyright © 2009 Pearson Education, Inc. Cellular Respiration: Cells Use Glucose and Oxygen to Supply ATP Glucose provides energy for the cell Copyright © 2009 Pearson Education, Inc. Figure 3.23 10 Stages of Cellular Respiration Glycolysis: in cytoplasm Splits glucose Produces two ATP and two pyruvate molecules Citric acid cycle: in mitochondria Also called the Krebs cycle Extracts high-energy electrons Produces two ATP and carbon dioxide Electron transport system: in mitochondria Energy from electrons is used to produce ATP Produces water and carbon dioxide Copyright © 2009 Pearson Education, Inc. Cellular Respiration: An Overview Copyright © 2009 Pearson Education, Inc. Figure 3.24 Glycolysis Copyright © 2009 Pearson Education, Inc. Figure 3.25 11 The Preparatory Step Copyright © 2009 Pearson Education, Inc. Figure 3.26 The Citric Acid Cycle Copyright © 2009 Pearson Education, Inc. Figure 3.27 Steps in the Electron Transport System Copyright © 2009 Pearson Education, Inc. Figure 3.28 12 Cellular Respiration: A Recap Copyright © 2009 Pearson Education, Inc. Figure 3.29a Fats and Proteins: Additional Energy Sources Copyright © 2009 Pearson Education, Inc. Figure 3.30 Fats and Proteins: Additional Energy Sources Fats Triglycerides have twice the energy of carbohydrates Proteins Same energy as carbohydrates Copyright © 2009 Pearson Education, Inc. 13 Anaerobic Pathways: Energy Extraction Without Oxygen Glucose (Glycolysis) (2) ATP Lactic acid buildup Pyruvate Mitochondrial metabolism blocked without oxygen Mitochondrion Copyright © 2009 Pearson Education, Inc. Figure 3.31 14