Power Point Lecture Slides prepared by Vince Austin
Power. Point® Lecture Slides prepared by Vince Austin, University of Kentucky Cells: The Living Units Part A Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings 3
Cell Theory § The cell is the basic structural and functional unit of life § Organism activity depends on individual and collective activity of cells § Biochemical activities of cells are dictated by subcellular structure § Continuity of life has a cellular basis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Structure of a Generalized Cell Figure 3. 2 Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Plasma Membrane § Separates intracellular fluids from extracellular fluids § Plays a dynamic role in cellular activity § Glycocalyx is a glycoprotein area abutting the cell that provides highly specific biological markers by which cells recognize one another Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Fluid Mosaic Model § Double bilayer of lipids with imbedded, dispersed proteins § Bilayer consists of phospholipids, cholesterol, and glycolipids § Glycolipids are lipids with bound carbohydrate § Phospholipids have hydrophobic and hydrophilic bipoles Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Draw simple Phospholipid Bilayer Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Fluid Mosaic Model Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 3. 3
Functions of Membrane Proteins § Transport § Enzymatic activity § Receptors for signal transduction Figure 3. 4. 1 Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Passive Membrane Transport: Diffusion § Simple diffusion – nonpolar and lipid-soluble substances § Diffuse directly through the lipid bilayer Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Passive Membrane Transport: Osmosis § Occurs when the concentration of a solvent is different on opposite sides of a membrane § Osmosis: diffusion of water across a semi-permeable membrane § Osmolarity – total concentration of solute particles in a solution § Tonicity – how a solution affects cell volume Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Effects of Solutions of Varying Tonicity § Isotonic – solutions with the same solute concentration as that of the cytosol § Hypertonic – solutions having greater solute concentration that of the cytosol § Hypotonic – solutions having lesser solute concentration that of the cytosol Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Effect of Membrane Permeability on Diffusion and Osmosis Figure 3. 8 b Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Passive Membrane Transport: Filtration § The passage of water and solutes through a membrane by hydrostatic pressure § Pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Diffusion Through the Plasma Membrane Figure 3. 7 Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Passive Membrane Transport: Diffusion § Facilitated diffusion § Transport of glucose, amino acids, and ions § Transported substances bind carrier proteins or pass through protein channels § Are integral trans-membrane proteins § Show specificity for certain polar molecules including sugars and amino acids Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Process of Facilitated Diffusion § Protein binds with molecule § Shape of protein changes § Molecule moves across membrane Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Facilitated Diffusion Ion CHANNELS Membrane proteins create a tunnel through which Ions can pass. http: //bio. winona. edu/berg/ANIMTNS/voltgate. htm Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Active Transport that require energy to move molecules against the concentration gradient. Cell example: Want to put MORE glucose into mitochondria when there is already glucose in there. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Image from: http: //www. biologyclass. net/mitochondria. jpg
Active Transport § Two Types of Active Transport. § Pumps § Cytosis. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Pumps § Carrier proteins that change shape for molecules that are not the correct shape. § Completely changing shape requires energy. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Sodium-Potassium Pump 6 K+ is released and Na+ sites are ready to bind Na+ again; the cycle repeats. Extracellular fluid 1 Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP. Cytoplasm 2 Phosphorylation causes the protein to change its shape. Concentration gradients of K+ and Na+ 3 The shape change expels 5 Loss of phosphate restores the original conformation of the pump protein. Na+ to the outside, and extracellular K+ binds. 4 K+ binding triggers release of the phosphate group. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 3. 10
Vesicular Transport § Transport of large particles and macromolecules across plasma membranes § Exocytosis – moves substance from the cell interior to the extracellular space § Endocytosis – enables large particles and macromolecules to enter the cell Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Vesicular Transport § Transcytosis – moving substances into, across, and then out of a cell § Vesicular trafficking – moving substances from one area in the cell to another Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Exocytosis Figure 3. 12 a Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Forms of Endocytosis § Phagocytosis – cell eating § Pinocytosis – cell drinking Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
WHITE BLOOD CELL ENGULFING BACTERIA (Phagocytosis) Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings http: //fig. cox. miami. edu/~cmallery/255 ion/fig 14 x 28. jpg
INSULIN being released by pancreas cells using exocytosis http: //fig. cox. miami. edu/~cmallery/255 ion/fig 14 x 26. jpg Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Passive Membrane Transport – Review Process Energy Source Example Simple diffusion Kinetic energy Movement of O 2 through membrane Facilitated diffusion Kinetic energy Movement of glucose into cells Osmosis Kinetic energy Movement of H 2 O in & out of cells Filtration Hydrostatic pressure Formation of kidney filtrate Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Active Membrane Transport – Review Process Energy Source Example Active transport of solutes ATP Movement of ions across membranes Exocytosis ATP Neurotransmitter secretion Endocytosis ATP White blood cell phagocytosis Fluid-phase endocytosis ATP Absorption by intestinal cells Receptor-mediated endocytosis ATP Hormone and cholesterol uptake Endocytosis via caveoli ATP Cholesterol regulation Endocytosis via coatomer vesicles ATP Intracellular trafficking of molecules Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Functions of Membrane Proteins § Intercellular adhesion § Cell-cell recognition § Attachment to cytoskeleton and extracellular matrix Figure 3. 4. 2 Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Plasma Membrane Surfaces § Differ in the kind amount of lipids they contain § Glycolipids are found only in the outer membrane surface § 20% of all membrane lipid is cholesterol Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Membrane Junctions § Tight junction – impermeable junction that encircles the cell § Desmosome – anchoring junction scattered along the sides of cells § Gap junction – a nexus that allows chemical substances to pass between cells Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Membrane Junctions: Tight Junction Figure 3. 5 a Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
Membrane Junctions: Desmosome Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 3. 5 b
Membrane Junctions: Gap Junction Figure 3. 5 c Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings
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