Chapter 3 : Part ACell TheoryCell DiversitySlide 4Generalized CellSlide 6Plasma MembraneSlide 8Membrane LipidsFunctions of Membrane ProteinsSlide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Membrane TransportTypes of Membrane TransportPassive ProcessesSlide 21Passive Processes: Simple DiffusionSlide 23Passive Processes: Facilitated DiffusionFacilitated Diffusion Using Carrier ProteinsSlide 26Facilitated Diffusion Using Channel ProteinsSlide 28Passive Processes: OsmosisSlide 30Slide 31Slide 32Slide 33Importance of OsmosisTonicitySlide 36Cells: The Living UnitsThe cell is the smallest structural and functional living unit Organismal functions depend on individual and collective cell functionsBiochemical activities of cells are dictated by their specific sub cellular structures called organellesOver 200 different types of human cellsTypes differ in size, shape, subcellular components, and functionsCopyright © 2010 Pearson Education, Inc.FibroblastsErythrocytesEpithelial cells(d) Cell that fights diseaseNerve cellFat cellSperm(a) Cells that connect body parts, form linings, or transport gases(c) Cell that storesnutrients(b) Cells that move organs and body parts(e) Cell that gathers information and control body functions(f) Cell of reproductionSkeletalMusclecellSmoothmuscle cellsMacrophageFigure 3.1 All cells have some common structures and functions Human cells have four basic parts:◦Plasma membrane - flexible outer boundary◦Cytoplasm - intracellular fluid◦Organelles - multiple functions◦Nucleus - control centerCopyright © 2010 Pearson Education, Inc.Figure 3.2Secretion beingreleased from cellby exocytosisPeroxisomeRibosomesRoughendoplasmicreticulumNucleusNuclear envelopeChromatinGolgi apparatusNucleolusSmooth endoplasmicreticulum CytosolLysosomeMitochondrionCentriolesCentrosomematrixCytoskeletalelements• Microtubule• Intermediate filamentsPlasmamembraneBimolecular layer of lipids and proteins in a constantly changing fluid mosaic Plays a dynamic role in cellular activitySeparates intracellular fluid (ICF) from extracellular fluid (ECF)◦Interstitial fluid (IF) = ECF that surrounds cellsCopyright © 2010 Pearson Education, Inc.Figure 3.3Integralproteins Extracellular fluid(watery environment)Cytoplasm(watery environment) Polar head ofphospholipid moleculeGlycolipidCholesterolPeripheralproteins Bimolecularlipid layercontainingproteinsInward-facinglayer ofphospholipidsOutward-facinglayer ofphospholipidsCarbohydrate of glycocalyxGlycoproteinFilament of cytoskeletonNonpolar tail of phospholipid moleculePhospholipids (lipid bilayer) ◦Phosphate heads: polar and hydrophilic◦Fatty acid tails: nonpolar and hydrophobic (Review Fig. 2.16b)1. Transport2. Receptors for signal transduction3. Attachment to cytoskeleton and extracellular matrixCopyright © 2010 Pearson Education, Inc.Figure 3.4aA protein (left) that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute. Some transport proteins (right) hydrolyze ATP as an energy source to actively pump substances across the membrane.(a) TransportCopyright © 2010 Pearson Education, Inc.Figure 3.4bA membrane protein exposed to the outside of the cell may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external signal may cause a change in shape in the protein that initiates a chain of chemical reactions in the cell.(b) Receptors for signal transductionSignalReceptorCopyright © 2010 Pearson Education, Inc.Figure 3.4cElements of the cytoskeleton (cell’s internal supports) and the extracellular matrix (fibers and other substances outside the cell) may be anchored to membrane proteins, which help maintain cell shape and fix the location of certain membrane proteins. Others play a role in cell movement or bind adjacent cells together.(c) Attachment to the cytoskeleton and extracellular matrix (ECM)4. Enzymatic activity5. Intercellular joining6. Cell-cell recognitionCopyright © 2010 Pearson Education, Inc.Figure 3.4dA protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution. In some cases, several enzymes in a membrane act as a team that catalyzes sequential steps of a metabolic pathway as indicated (left to right) here.(d) Enzymatic activityEnzymesCopyright © 2010 Pearson Education, Inc.Figure 3.4eMembrane proteins of adjacent cells may be hooked together in various kinds of intercellular junctions. Some membrane proteins (CAMs) of this group provide temporary binding sites that guide cell migration and other cell-to-cell interactions.CAMs(e) Intercellular joiningCopyright © 2010 Pearson Education, Inc.Figure 3.4fSome glycoproteins (proteins bonded to short chains of sugars) serve as identification tags that are specifically recognized by other cells.(f) Cell-cell recognitionGlycoproteinPlasma membranes are selectively permeableSome molecules easily pass through the membrane; others do notPassive processes◦No cellular energy (ATP) required◦Substance moves down its concentration gradientActive processes◦Energy (ATP) required◦Occurs only in living cell membranesWhat determines whether or not a substance can passively permeate a membrane?1. Lipid solubility of substance2. Channels of appropriate size3. Carrier proteinsPLAYPLAYAnimation: Membrane PermeabilitySimple diffusionCarrier-mediated facilitated diffusionChannel-mediated facilitated diffusionOsmosisNonpolar lipid-soluble (hydrophobic) substances diffuse directly through the phospholipid bilayerDiffusion is the movement of solutes from a solution of higher concentration to that of a lower concentrationPLAYPLAYAnimation: DiffusionCopyright © 2010 Pearson Education, Inc.Figure 3.7aExtracellular fluidLipid-solublesolutesCytoplasm(a) Simple diffusion of fat-soluble molecules directly through the phospholipid bilayerCertain lipophobic molecules (e.g., glucose, amino acids, and ions) use carrier proteins or channel proteins, both of which:◦Exhibit specificity (selectivity)◦Are saturable; rate is determined by number of carriers or channels◦Can be regulated in terms of activity and quantityTransmembrane integral proteins transport specific polar molecules (e.g., sugars and amino acids)Binding of substrate causes shape change in carrierCopyright © 2010 Pearson Education, Inc.Figure