BIOLOGY 111 1st Edition Lecture 8 Outline of Last Lecture I. Cell sizeII. Prokaryotic CellIII. Plasma membraneIV. Eukaryotic cellA. Animal B. PlantV. Endosymbiont TheoryOutline of Current Lecture I. MicrotubulesII. MicrofilamentsIII. Intermediate FilamentsIV. Membrane Structure and FunctionCurrent LectureMicrotubules “tubulin polymers”- Made up of tubulin, 13 columns of hollow tubes- Functions:- Maintain cell shape - Cell motility (cilia and flagella)- Chromosome movements in cell division- Organelle movementsMicrofilaments “actin filaments”- Made up of actin, two intertwined strands- Found mostly in muscle- Functions: - Maintain and changes cell shape – anchored cellular extensions These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Muscle contraction – Myosin motors in muscle cells, contraction is a result of actin and myosin sliding past each other, shortening the cell… - Cytoplasmic streaming – circular flow of cytoplasm within plant cells, speeds up the distribution of materials within the cello Nonmoving cortical cytoplasm (gel)o Moving streaming cytoplasm (sol)- Cell motility and divisionIntermediate Filaments- Made up of Keratin and is supercoiled (*keratin found in hair and skin)- Functions:- Maintain cell shape- Anchorage of nucleus and certain other organelles- Formation of nuclear laminaChapter 7Membrane Structure and Function- Acts as a selective gate, allowing some things to enter and leavePlasma membrane – is a boundary that separates living cell from its surroundings and is selectively permeable and dynamic (constantly changing to adapt to changing environments)- made up of phospholipids (amphipathetic), most abundant lipids, spontaneously form bilayers in aqueous environmentso polar need help, non-polar enter with not problemso amphipathetic - loving and fearing water - lipids are o laterally mobile (everything moves sideways) - most commono rotational movements - rotate on own axiso flip-flop - flippase catalyzes the two layers to switch placewhy do they move? o fluidity is affected by degree of saturation (saturated vs unsaturated bonds) -more unsaturated bonds, more fluid-more saturated bonds, more viscous (solid state)These changes also depend on environment-ex. unsaturated in hot environment would make more liquid state, saturated in cold would be more solid-plasma membrane of cells in extreme cold would probably be made more of unsaturated to maintain fluidity- cells in very extreme high temps, expect more saturated to maintain fluidityhumans have equal ration of saturated and unsaturated bc not living in an extreme environment- Cholesterol - main component of plasma membraneo acts as a buffer in resisting temperature changes at high temperatures, restrains phospholipid movement and holds them together at low temperatures, does not allow packing of phospholipids*Proteins determine most of the membranes specific functionIntegral membrane located embedded in the lipid bilayer (Intrinsic and Extrinsic)function: Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attaches cytoskeleton and ExtraCellular Membrane (ECM)- transmembrane - span the membrane in alpha helices (almost 30% of genes encoded for all organisms)Peripheral membrane located on outside of membrane (not embedded in lipid bilayer) - Glycoprotein – protein with one or more covalently attached carbohydrates- Glycolipids – lipid with one or more covalently attached carbohydrates- Carbohydrates – mono-, di-, or polysaccharides- Extracellular leaflet - - Cytosolic leaflet- cholesterol found only in animalsPermeability- High permeability (gases (nonpolar), very small uncharged polar molecules) - needs no help- Moderate (water and urea) - needs some help- Low (polar organic molecules) - needs lots of help- Very low (ions and charged polar molecules and macromolecules) - will not go through not matter whatPassive transport is diffusion across a membrane with no energy investment Diffusion - tendency for molecules to spread out evenly into available spaceFacilitated diffusion - transport proteins speed the passive movement of molecules across the plasma membranechannel proteins - allow passage of hydrophilic substances across the membranecarrier proteins - bind molecule and change shape to shuttle them across the