Bios 138 Cell Biology and Respiration 2 PDF

Because learning changes everything. ® Chapter 03 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or...

Because learning changes everything. ® Chapter 03 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Energy, Chemical Reactions, and Cellular Respiration All living organisms require energy to Power muscle Pump blood Absorb nutrients Exchange respiratory gases Synthesize new molecules Establish cellular ion concentrations Glucose broken down through metabolic pathways Forms ATP, the “energy currency” of cells Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 3.1a Classes of Energy 1 Energy Energy is the capacity to do work Two classes of energy Potential energy—energy of position or stored energy Kinetic energy—energy of motion Both can be converted from one class to the other Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3 3.1c Laws of Thermodynamics Thermodynamics—study of energy transformations First law of thermodynamics Energy can neither be created nor destroyed; it can only change in form Second law of thermodynamics When energy is transformed, some energy is lost to heat The amount of usable energy decreased For example, moving around to warm up on a cold day As chemical energy converts to mechanical energy, heat is produced Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 3.2a Chemical Equations 1 Metabolism All biochemical reactions in living organisms Chemical reactions Occur when chemical bonds in existing molecular structures are broken New bonds formed Expressed as chemical equation Reactants Products Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 3.2a Chemical Equations 2 Reactants Substances present prior to start of a chemical reaction Written on left side of equation Products Substances formed by the reaction Written on right side of equation A+B → C A and B are reactants C is the product Arrow indicates reaction direction In a balanced equation, number of elements are equal on both sides of the reaction Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6  3.2b Classification of Chemical Reactions 2 Decomposition reaction Initial large molecule broken down into smaller structures AB → A + B For example, hydrolysis reaction of sucrose into glucose and fructose All decomposition reactions in the body are referred to as catabolism or catabolic reactions Figure 3.4a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7  3.2b Classification of Chemical Reactions 3 Synthesis reaction Two or more structures combined to form a larger structure A + B → AB For example, dehydration synthesis reaction forming a dipeptide Anabolism (anabolic reactions) is the collective term for all synthesis reactions in the body Figure 3.4b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8  3.2b Classification of Chemical Reactions 4 Exchange reaction Groups exchanged between two chemical structures Has both decomposition and synthesis components Most prevalent in human body AB + C → A + BC For example, production of ATP in muscle tissue Figure 3.4c Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 3.2b Classification of Chemical Reactions 6 Classifying Changes in Chemical Energy Exergonic reactions Reactants with more energy within their chemical bonds than products Energy released with net decrease in potential energy For example, decomposition reactions Endergonic reactions Reactants with less energy within their chemical bonds than products Energy supplied with a net increase in potential energy For example, synthesis reactions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10  Exergonic and Endergonic Reactions Figure 3.6 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 3.2b Classification of Chemical Reactions 7 ATP cycling Continuous formation and breakdown of ATP ATP formed when energy is released in exergonic reactions Fuel molecules from food are oxidized Energy in their bonds transferred to ADP and free phosphate to form ATP ATP oxidized to aid endergonic reactions Energy released from ATP hydrolysis provides energy Only a few seconds worth of ATP present at a time Formation of ATP occurs continuously to provide energy Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12  ATP Cycling Figure 3.7 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13 3.3a Function of Enzymes Enzymes Biologically active catalysts that accelerate chemical reactions Only facilitate reactions that would already occur Increase rate of product formation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14  Enzyme Structure Active site’s specificity Permits only a single substrate to bind Helps catalyze only one specific reaction Figure 3.9 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15  Mechanism of Action for an Enzyme in a Decomposition Reaction Figure 3.10a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16  Mechanism of Action for an Enzyme in a Synthesis Reaction Figure 3.10b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 3.3d Classification and Naming of Enzymes 2 Enzyme names based on Name of substrate or product Subclass Suffix –ase For example, pyruvate dehydrogenase transfers hydrogen from pyruvate For example, DNA polymerase helps form DNA For example, lactase digests lactose Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 3.3e Enzymes and Reaction Rates 3 Effect of pH Enzymes function best at optimal pH Between pH of 6 and 8 for most enzymes Changes in H+ disrupt electrostatic interactions Enzyme loss of shape, denaturation Optimal pH may differ For example, enzymes working in the lower pH of the stomach Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19  Effect of pH on Enzyme Activity Figure 3.11c Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 3.3f Controlling Enzymes Inhibitors bind enzymes and turn them off Prevents overproduction of product Later release of inhibitor allows enzyme to function again Inhibitors can be competitive or noncompetitive Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21  Competitive Inhibitor Competitive inhibitor Resembles substrate and binds to active site of enzyme Compete for occupation of active site With greater substrate Less likely competitive inhibitor will occupy site With less substrate More likely inhibitor will occupy site Figure 3.12b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22  Noncompetitive Inhibitor Noncompetitive inhibitors Do not resemble substrate Bind a site other than active site (allosteric site) Induce conformational change to enzyme and active site Also called allosteric inhibitors Not influenced by concentration of substrate Figure 3.12c Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 3.4 Cellular Respiration Exergonic multistep metabolic pathway Organic molecules oxidized and disassembled by a series of enzymes Potential energy in chemical bonds released synthesizes ATP (which is an endergonic process) Oxygen required for maximum ATP production Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24 3.4a Overview of Glucose Oxidation 1 Glucose oxidation Step-by-step breakdown of glucose with energy release Carbon dioxide and water formed Glucose Energy-rich molecule with many C—C, C—H, C—O bonds Net chemical reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25  Cellular Structures Required for Cellular Respiration Figure 3.15 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26 3.4a Overview of Glucose Oxidation 4 Four stages of glucose oxidation: 1. Glycolysis Occurs in cytosol Does not require oxygen 2. Intermediate stage 3. Citric acid cycle 4. Electron transport system Stages 2, 3, and 4 Occur in mitochondria Require oxygen Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 3.4b Glycolysis 1 Glycolysis Does not require oxygen Glucose broken down into two pyruvate molecules Net production of 2 ATP and 2 NADH molecules Glucose is the initial substrate Pyruvate is the final product Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 28 3.4b Glycolysis 2 The fate of pyruvate depends on oxygen availability If sufficient O2 available, pyruvate enters mitochondria If insufficient O2 available, pyruvate converted to lactate Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 3.4c Intermediate Stage 1 Remaining stages of cellular respiration are aerobic processes that occur within mitochondria Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30  Intermediate Stage Figure 3.17 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31  3.4d Citric Acid Cycle 1 Cyclic metabolic pathway Figure 3.18a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32  Citric Acid Cycle Figure 3.18b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 3.4d Citric Acid Cycle 3 Summary of the citric acid cycle Occurs in mitochondria Requires oxygen Two CO2 and one CoA produced 1 ATP, 3 NADH, 1 FADH2 formed per cycle Two “turns” for one glucose molecule 2 ATP, 6 NADH, 2 FADH2 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 3.4e The Electron Transport System 1 Function of the electron transport system Transfer of electrons from NADH and FADH2 to make ATP Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35  The Electron Transport System Figure 3.19 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36  Summary of Stages of Cellular Respiration Figure 3.20 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 3.4f ATP Production 2 ATP in glucose breakdown Stage/Total Substrate-level phosphorylation Oxidative phosphorylation Glycolysis 2 ATP 2 NADH → 6 ATP Intermediate Stage –– 2 NADH → 6 ATP Citric Acid Cycle 2 ATP 6 NADH → 18 ATP 2 FADH2 → 4 ATP Total 2 ATP 34 ATP Some ATP used during cellular respiration, so net ATP is 30 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 3.4g The Fate of Pyruvate with Insufficient Oxygen 1 If insufficient oxygen: 1. Activity of electron transport chain decreases Levels of NADH and FADH2 accumulate Decreased levels of NAD+ and FAD 2. Cell becomes more dependent upon glycolysis Requires NAD+ to continue 3. Glycolysis eventually shuts down Due to lack of NAD + 4. NAD must be regenerated for glycolysis to continue Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39  3.4g The Fate of Pyruvate with Insufficient Oxygen 2 Pyruvate converted to lactate (lactic acid) Enables glycolysis to continue Only 2 ATP generated versus 30 with sufficient oxygen Impacts individuals with decreased ability to deliver oxygen to cells For example, those with respiratory or cardiovascular disease Figure 3.21 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40  End of Main Content Because learning changes everything. ® www.mheducation.com Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Chapter 04 Lecture Outline Anatomy & Physiology AN INTEGRATIVE APPROACH Fourth Edition Michael P. McKinley Valerie Dean O’Loughlin Theresa Stouter Bidle Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  4.1c Common Features and General Functions 1 Plasma membrane Forms outer, limiting barrier separating internal contents from external environment Modified extensions of plasma membrane Cilia, flagellum, microvilli Nucleus Largest structure in cell; enclosed by a nuclear envelope Contains genetic material (DNA); also contains a nucleolus Nucleoplasm—inner fluid Cytoplasm Cellular contents between plasma membrane and nucleus Includes: cytosol, organelles, and inclusions 43  4.1c Common Features and General Functions 2 Cytoplasmic components Cytosol (intracellular fluid ) Viscous fluid of cytoplasm High water content Contains dissolved macromolecules and ions Organelles (“little organs”) Complex, organized structures within cells Unique shapes and functions Two categories Membrane-bound organelles Non-membrane-bound organelles 44  4.1c Common Features and General Functions 3 Organelles (“little organs”) (continued ) Membrane-bound organelles Enclosed by a membrane Separates contents from cytosol Includes endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria Non-membrane-bound organelles Not enclosed within a membrane Composed of protein Includes ribosomes, cytoskeleton, centrosome, proteasomes 45  4.1c Common Features and General Functions 5 Cells perform general functions: Maintain integrity and shape of a cell Dependent on plasma membrane and internal contents Obtain nutrients and form chemical building blocks Harvest energy for survival Dispose of wastes Avoid accumulation that could disrupt cellular activities Some are also capable of cell division Make more cells of same type Help maintain tissue by providing cells for new growth and replacing dead cells 46  4.2a Lipid Components 1 Plasma membrane Fluid mixture composed of equal parts lipid and protein by weight Regulates movement of most substances in and out of cell Contains several different types of lipids: Phospholipids Cholesterol Glycolipids 47  4.2a Lipid Components 2 Phospholipids “Balloon with two tails” Polar and hydrophilic “head”; two nonpolar and hydrophobic “tails” Form two parallel sheets of molecules lying tail to tail Hydrophobic tails form internal environment of membrane Hydrophilic polar heads directed outward Phospholipid bilayer is the basic structure of the framework Ensures cytosol remains inside the cell Ensures interstitial fluid/EXTRACELLULAR remains outside 48  Structure and Functions of the Plasma Membrane (b) ©Don W. Fawcett/Science Source Figure 4.5 Access the text alternative for slide images. 49  4.2b Membrane Proteins 1 Membrane proteins Half of plasma membrane by weight Float and move in fluid bilayer Performs most of membrane’s functions Two structural types Integral Peripheral 50  4.2b Membrane Proteins 3 Proteins are also categorized functionally: Transport proteins Regulate movement of substances across membrane For example, channels, carrier proteins, pumps, symporters, and antiporters Cell surface receptors Bind molecules called ligands For example, neurotransmitters released from a nerve cell that binds to a muscle cell to initiate contraction Identity markers: Self vs. Not Self Communicate to other cells that they belong to the body These markers are used to distinguish healthy cells from cells to be destroyed 51  4.2b Membrane Proteins 4 Functional categories of proteins (continued ) Enzymes May be attached to either internal or external surface of a cell Catalyze chemical reactions Anchoring sites Secure cytoskeleton to plasma membrane Cell-adhesion proteins Perform cell-to-cell attachments 52  Plasma Membrane Proteins Figure 4.6 Access the text alternative for slide images. 53  4.3 Membrane Transport 1 Plasma membrane Serves as physical barrier between cell and fluid that surround it (interstitial fluid) Regulates movement into and out of a cell Establishes and maintains electrochemical gradient Functions in cell communication Membrane transport Process of obtaining and eliminating substance across the plasma membrane Two categories Passive processes Active processes 54  Membrane Transport Key Concept Water follows solute Substances move from areas of high concentration to areas of low concentration until an equilibrium is reached 55  Membrane Transport Figure 4.7 Access the text alternative for slide images. 56  4.3 Membrane Transport 2 Substances moved across a membrane Passive processes of membrane transport Do not require energy Depend on substances moving down concentration gradient Move from area of more substance to area of less Two types: diffusion, osmosis Active processes of membrane transport Require energy Substance must be moved up its concentration gradient (active transport) Membrane-bound vesicle must be released (vesicular transport) 57  4.3a Passive Processes: Diffusion 1 Diffusion Net movement of ions or molecules from area of greater concentration to area of lesser concentration Down the concentration gradient Also influenced by “steepness” of concentration gradient Measure of the difference in concentration between two areas Steeper gradient causes faster rate of diffusion If unopposed, diffusion continues until substance reaches equilibrium Molecules evenly distributed throughout a given area 58  Diffusion Figure 4.8 59  Simple Diffusion of Solutes Figure 4.9 Access the text alternative for slide images. 60  4.3a Passive Processes: Diffusion 4 Facilitated diffusion Transport process for small charged or polar solutes requires assistance from plasma membrane proteins Two types: Channel-mediated diffusion Carrier-mediated diffusion 61  Channel-Mediated Diffusion Figure 4.10a Access the text alternative for slide images. 62  4.3a Passive Processes: Diffusion 6 Carrier-mediated diffusion Small polar molecules assisted across membrane by carrier protein Binding of substance causing change in carrier protein shape Releases substances on other side of membrane 63  Carrier-Mediated Diffusion Figure 4.10b Access the text alternative for slide images. 64  4.3b Passive Processes: Osmosis 1 Osmosis Movement of water, not solutes Passive movement of water through semipermeable membrane Osmosis is promoted by differences in water concentration on either side of a membrane 65  Osmosis in Cells Figure 4.11 Access the text alternative for slide images. 66  4.3b Passive Processes: Osmosis 5 Osmosis and tonicity cells gain or lose water with osmosis and that changes the cell volume Tonicity—ability of a solution to change the volume or pressure of a cell by osmosis Terms that describe relative concentration of solutions: Isotonic Hypotonic Hypertonic 67  4.3b Passive Processes: Osmosis 6 Isotonic solution Both cytosol and solution have same relative concentration of solutes For example, normal saline with a concentration of 0.9% NaCl Commonly used in IV solutions No net movement of water 68  4.3b Passive Processes: Osmosis 7 Hypotonic solution Solution has a lower concentration of solutes, higher concentration of water than in cytosol For example, erythrocytes in pure water Water moves down concentration gradient from outside cell to inside Increases volume and pressure of cell Lysis—rupturing of red blood cells occurs if difference is large enough Hemolysis—rupturing erythrocytes 69  4.3b Passive Processes: Osmosis 8 Hypertonic solution Solution with a higher concentration of solutes than cytosol For example, erythrocytes in 3% NaCl water solution Water moves down concentration gradient Moves from inside cell to outside Decreases volume and pressure of cell Crenation—cell shrinks 70  Erythrocytes Immersed In Three Different Solution Concentrations ©Dennis Kunkel Microscopy, Inc./Medical Images Figure 4.13 Access the text alternative for slide images. 71  4.3c Active Processes 1 Active processes are organized into active transport and vesicular transport Active transport Movement of a solute against its concentration gradient (that is, from lower to higher concentration) Maintains gradient between cell and interstitial fluid Requires energy 72  4.3c Active Processes 3 Ion pumps Cellular protein pumps that move ions across membrane Maintain internal concentrations of ions For example, Ca2+ pumps in plasma membrane of erythrocytes Prevent cell rigidity from accumulated calcium Erythrocytes remain flexible enough to move Figure 4.14 Access the text alternative for slide images. 73  4.3c Active Processes 4 Sodium-potassium (Na/K) pump Type of exchange pump Moves one type of ion into cell against gradient, while moving another type of ion out of cell against gradient Plasma membrane preserves steep gradient differences Continuously exports Na+ out of the cell and moves K into the cell Must be working for cell to survive! 74  Na+/K+ Pump Figure 4.15 Access the text alternative for slide images. 75  4.3c Active Processes 7 Vesicular transport Also called bulk transport Involves energy input to transport large substances across the plasma membrane by a vesicle Membrane-bounded sac filled with materials Organized into processes of Exocytosis- out of the cell Endocytosis- into the cell 76  Exocytosis Figure 4.17 Access the text alternative for slide images. 77  4.3c Active Processes 10 Three types of endocytosis: phagocytosis, pinocytosis, receptor- mediated endocytosis Phagocytosis Cellular eating Occurs when a cell engulfs a large particle external to cell They surround particle, enclosing it in a membrane sac Sac is internalized, contents digested after fusing with lysosome Only a few cell types perform this For example, when a white blood cell engulfs and digests a microbe 78  Phagocytosis 1 Figure 4.18a Access the text alternative for slide images. 79  4.3c Active Processes 11 Pinocytosis Cellular drinking Internalization of droplets of interstitial fluid containing dissolved solutes Multiple, small vesicles formed Performed by most cells 80  Pinocytosis 2 Figure 4.18b Access the text alternative for slide images. 81  4.4a Introduction Electrical charge difference at plasma membrane Membrane potential—potential energy of charge difference Resting membrane potential (RMP)—potential when a cell is at rest Two conditions for RMP: 1. Unequal distribution of ions/molecules across plasma membrane More K+ in cytoplasm than in interstitial fluid More Na+in interstitial fluid than in cytoplasm Due to Na+/K+ pumps 2. Unequal relative amounts of positive and negative charges More positive on outside than inside of cell 82  Resting Membrane Potential (RMP) Figure 4.20 Access the text alternative for slide images. 83  4.4b Establishing and Maintaining RMP 3 Maintaining an RMP Na/K pumps significant Maintains K+ and Na+ gradients following their diffusion Na+ pumped out K+ pumped in Opposite directions Against concentration gradient 84  4.5 Cell Communication Plasma membrane serves an important role in cell communication Structures such as glycolipids and glycoproteins facilitate both direct interaction between cells as well as recognition and response to external molecular signals 85  4.5b Ligand-Receptor Signaling Most cell communication occurs through ligands Molecules that bind with macromolecules Neurotransmitters from nerve cells and hormones from endocrine cells Important for controlling growth, reproduction, and other cellular processes 86  Channel-Linked Receptors Permit ion passage into or out of cells Occurs in response to neurotransmitter binding Help initiate electrical changes to RMP in muscle and nerve cells Figure 4.21a Access the text alternative for slide images. 87  4.6 Cellular Structures Membrane-bound organelles Non-membrane-bound organelles Vesicles for transport Structures extending from cell surface 88  4.6a Membrane-Bound Organelles 1 Membrane-bound organelles Surrounded by membrane Allows activities in isolated environment Endoplasmic Reticulum (ER) Extensive interconnected membrane network Point of attachment for ribosomes With ribosomes—rough ER RIBOSOMES MAKE PROTEINS Without ribosomes—smooth Smooth ER: Synthesis, transport, and storage of lipids 89  The Endoplasmic Reticulum (ER) (photo) ©Dennis Kunkel Microscopy, Inc./Medical Images Figure 4.22 Access the text alternative for slide images. 90  4.6a Membrane-Bound Organelles 3 Golgi apparatus Post office of the cell Composed of cisternae, elongated saclike membranous structures Functions: modification, packaging, and sorting of proteins Formation of secretory vesicles Some vesicles become part of plasma membrane Others release contents outside cell 91  The Golgi Apparatus and Endomembrane System (a) ©Biophoto Associates/Science Source Figure 4.23 Access the text alternative for slide images. 92  Lysosomes Small, membranous sacs Contain digestive enzymes formed by Golgi Participate in digestion of unneeded substances Digest contents of endocytosed vesicles Garbage disposal of the cell ©Science Source; (photo) ©McGraw-Hill Education Access the text alternative for slide images. 93  Peroxisomes The detoxifier Membrane-enclosed sacs, smaller than lysosomes Pinched off vesicles from rough ER Proteins are incorporated to serve as their enzymes Metabolic functions include Role in chemical digestion Lipid synthesis ©Don W. Fawcett/Science Source; (photo) ©McGraw-Hill Education/Electronic Publishing Services, Inc., NY Access the text alternative for slide images. 94  Mitochondria Oblong shaped organelles with double membrane Aerobic cellular respiration Complete digestion of fuel molecules to synthesize ATP “Powerhouses” of cell Cellular Respiration to ©Don W. Fawcett/Science Source Figure 4.26 make ATP Access the text alternative for slide images. 95  Proteasomes ©Edward P. Morris Figure 4.29 Access the text alternative for slide images. 96  4.6b Non-Membrane-Bound Organelles 4 Cytoskeleton Plays roles in Intracellular support Organization of organelles Cell division Movement of materials Extends throughout cell interior; anchor proteins in membrane Includes Microfilaments Intermediate filaments Microtubules 97  The Cytoskeleton Figure 4.30 Access the text alternative for slide images. 98 Molecular Motor Structure and Direction From Pollard T, Earnshaw W: Cell biology, revised reprint, international edition, ed 1, Philadelphia, 2004, Saunders.  4.6c Structures of the Cell’s External Surface Cilia Hair-like projections that move substances along cell surface Flagella Longer and wider than cilia; propels entire cell Microvilli Extensions of plasma membrane that increase surface area 100  Microvilli ©Don W. Fawcett/Science Source Figure 4.31 101  4.6d Membrane Junctions Tight junctions Strands or rows of proteins linking cells Prevent substances from passing between cells Requires materials to move through, rather than between cells Maintain polarity of epithelia Desmosomes Composed of proteins that bind neighboring cells Hemidesmosomes anchor basal layer of cells of epidermis to underlying components Gap junctions Form tiny, fluid-filled tunnels Provide direct passageway for substances to travel between cells (For example ions between cells in cardiac muscle) 102  Membrane Junctions Figure 4.32 Access the text alternative for slide images. 103  Structure of the Nucleus (a) ©Don W. Fawcett/Science Source Figure 4.34a Access the text alternative for slide images. 104  4.7b DNA, Chromatin, and Chromosomes 1 DNA Housed in nucleus Composed of repeated monomers (nucleotides) DNA has deoxyribonucleotides Each deoxyribonucleotide composed of Five-carbon sugar deoxyribose A phosphate One of four nitrogenous bases Adenine Cytosine Guanine Thymine 105  4.7b DNA, Chromatin, and Chromosomes 3 DNA (continued ) Each double helix is wound around nuclear proteins called histones Together form nucleosomes When not dividing, DNA are in form of finely filamented mass called chromatin When dividing, DNA chromatin becomes tightly coiled mass called chromosomes 106  DNA and Chromatin Structure Figure 4.34b Access the text alternative for slide images. 107  4.7b DNA, Chromatin, and Chromosomes 4 DNA and genes Genes = stretches of nucleotides that provide instructions for synthesis of specific proteins Figure 4.34c Access the text alternative for slide images. 108  4.8 Function of the Nucleus and Ribosomes Cellular activities dependent upon protein synthesis Directed by DNA Transcription Ribonucleic acid Copy of a gene formed from DNA in nucleus Translation Uses RNA for synthesis of protein by ribosomes in cytosol Access the text alternative for slide images. 109  Process of Transcription Figure 4.36 Access the text alternative for slide images. 110  4.8b Translation: Synthesizing Protein 1 Translation Synthesis of a new protein Occurs at ribosomes within cytoplasm mRNA threaded through ribosome Code in nucleotide sequence of mRNA translated Converted into amino acids to produce protein 111  4.8b Translation: Synthesizing Protein 5 Three events of translation: Initiation Elongation Termination 112  4.8c DNA as the Control Center of a Cell DNA directs synthesis of proteins that carry out body functions Indirectly responsible for other metabolic changes Synthesis of steroids Enzymatic pathway of glucose oxidation Controls enzymes responsible for decomposition and synthesis of chemical structures 113