Cell Structure (4.6-4.8)
Cell Structure (4.6-4.8) BIOL 201L 004
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BIOL 201L 004
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This 5 page Class Notes was uploaded by Feben Notetaker on Tuesday October 6, 2015. The Class Notes belongs to BIOL 201L 004 at Towson University taught by Dr. Sarah Texel in Fall 2015. Since its upload, it has received 57 views. For similar materials see Introduction to Cell Biology and Genetics in Biology at Towson University.
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Date Created: 10/06/15
Section 46 The Cytoskeleton Monday October5 2015 542 PM Cytoplasm is a network of proteins and fibers that support shape of cells 0 And anchors organelles Cytoskeleton network of proteins and fibers that make up the cytoplasm o Assembles and disassembles all the time Identical fibers have the same subunits that are attracted to each other 3 TYPES OF FIBERS M AKE U P CYTOSKELEI39ON httpwwwbiochemari zonaeduclassesbioc46 actinmicrofilaments O 7nm diameter 2462aNOTEScontractil Below the membrane e proteinACTIN2GIF Known as stress fibers and has a contractile function Two protein chains loosely twined around each other like two strands of pearl Each quotpearlquot is a protein called actin I Actin is polar and directs growth of filament M icrotubules o 25nm diameter 0 Made of a and B tublin protein subunits arranged side by side to form atube 0 Have stiff cytoskeleton elements 0 intracellular transport and separation of chromosomes during mitosis Intermediate filaments O 810nm diameter 0 Overlapping staggered tetramers of protein I Tetramers bundled into cable 0 Gives a ropelike structure that gives cell mechanical strength 0 EX Keratin vimentin Proteins in cells act as an on and off switch to regulate rate of actin polymerization Actin are responsible for movement in the cell and other contractions Filaments in nerve cells are called neurofilments O O O O CEN TRIOLES Centrioles barrel shaped organelles found in animal cells mostly protists Found in pairs right angles to each other or nuclear membrane Centrosome region surrounding the paired centrioles Pericentriolar material surrounds centrioles in centrosome o Hasringed structure made of tubulin 0 It39s a microtubules organizing center I Used to make microtubules in the cell Actin filaments and microtubules orchestrate cell functions such as cell reproduction Newly made chromosomes move to opposite sides of the cell bc of the shortening of microtubules In animals cells actin causesthe cell to contract to form a purse string Actin functions w myosin in muscle cellsto cause muscle contractions Cytoskeleton organizes the cell39s different activities by enzymes bonding to filaments ribosomes Cell Structure pt 2 Page 1 M icrotubules tubulin a tubulin Mum mm mm FM in c u w n7 i q s z z r 1 httporegonstateeduinstructionbi314sum m er09FI 1242039 r F I ll I 19 Monomer Sheet olquot BTetramers F 7 1 il39etramer lug Hire httplmicromgqnetfsueducellsintermedi atefilamentsimagesintermediatefilamentsfi gure1ipg Roipellke Filament Bundle Section 47 Extracellular Structures and Cell Movement Monday October 5 2015 543 PM Movement is related to the arrangement and movement of actin filaments o Myosin works alongside actin The arrangement of actin filament can allow cellsto crawl 0 Essential movement for inflammation blood clotting and spread of blood cancer 0 White blood cells have this ability Eukaryotic flagella is made of a circle of 9 microtubules pairs surrounding 2 92 structure microtubules o Goes up and down instead of rotating Cilia has an organization similar to the 92 structure 0 Short cellular projectionsthat are organized in rows 0 More than flagella but similar structure CELLWALLS EXTRACEIJU LAR M ATRIX ECM Cell walls in plants fungi and protists support and protect the cell Plants and protists have cell walls made of polysacchride cellulose Fungi have cell walls made of chitin Primary cell wall laid down when cell is still growing between walls and a sticky substance Middle lamella sticky substance that glues cellstogether Secondary cell wall deposited inside fully grown primary cell walls Proteoglycan complex Carbohydrates ECM Instead of cell walls animal cells secrete glycoproteins that surround the cell 0 Collagen O Eastin O Proteoglycan complex web of glycoproteins I Forms protective layer of cell surface Some ECM is attached to the cell membrane with aglycoprotein called fibronectin lntegrins also bind to fibronectin 0 They bind to microfilaments and intermediate filaments of the cytoskeleton 0 Allow ECM to influence cell behavior I Alter gene expression I cell migration 0 They send a combo of mechanical and chemical pathways 0 Coordinates behavior of cells in a tissue Collagen fiber Microfilaments T of the cytoskeleton Plasma lrltegrin membrane httpfiquresbou ndlesscom1 861 0fullfiqure0406 01ipeg Cell Structure pt 2 Page 2 Section 48 CelltoCell Interactions Monday October 5 2015 543 PM Cell surface identifies them Cells of the same tissue recognize each other through contact 0 They connect with each other to function properly Glycolipids cell surface markersthat are lipids with carb heads 0 Responsible for type A B O in blood cells Major Histocompatibility Complex M HC cell surface markersthat helps distinguish between foreign and nonforeign in body for immune system Multicellularity arose independently between species Proteins that form connections between cells are ancient Nature and function of each cell and how they connect determine the function of the tissue ADHERENSJJNCTIONS First to evolve Can be found in sponges In all animal cells They mechanincally attach to other cells39 cytoskeleton or to the ECM Usually found in found in cells dealing with mechanical stress like muscles and skin Adherensjunctions based on protein cadherin Cadherin a Ca2 dependent adhesion molecule 0 Single passtransmembrane protein with an extra cellular domain that can interact with the extracellular domain of other cells and join them together 0 Two types Type land II I When cellsthat have type or type II are mixed they rearrange to have Ito or II to II interactions I There is very little interaction between land cadherins 0 On the cytoplasmic side they interact indirectly through proteins such as actin to make flexible interactions Protein linking S calenin lo E cytoskeleton lcfln filament Cadherin neg mcatemnj Tatum 1 Extracellular jicatenin Signals transmitted to cytoplasm O httpccftpscueducn8090Downloaduploadfile20120810143217814qu DESM OSOM ES Desmosomes cadherin base junctions dependent on vertebrates 0 They have the canhedrins desmocollin and desmoglein I They interact with cytoskeleton instead of actin 0 Join adjacent cells help with mechanical stress 0 Hemidesmosome and focal adhesions connect cellsto basal lamina or ECM Cell Structure pt 2 Page 3 V Cadiherine 39 of cell 2 intermediate filaments of cell i 739 Intermediate V laments Magma of cell 2 membrane Badherine Extracelluar Plasma membrane pf cell 1 of cell 1 space of cell 2 httpsfiquresboundlesscom18613larqefiqureO40604ipe INTEGRIN Integrin Proteinsthat interact with ECM O Integrins are a part of cell surface receptors in integral proteins 0 20 different kinds exist each with a different binding domain Integrins interact with cytoskeleton actin filaments at focal adhesions and intermediate filaments at the hemidesmosome SEPTATE Septate Junction found in both invertebrates and vertebrates 0 Forms barriersto shut off a sheet of cells 0 Proteinsfound in these junctions have diff names 0 EX Drosophila I Discs large I Neurexin 0 Wide distribution indicatesthat they evolved soon after or with adherensjunctions Cherdates Drosophila ght thrtE l it n Elll l39tElFl39if39lii b junction septa ti julti I i httplabscsbutorontocatepass Research filesAJGDroChorJJIy2007qu TIGHT Tight Junction only in vertebrates 0 Have proteins called Claudins I They block or exclude substances from passing between cells I Acts asawall in atissue Creating sheets of cells cells in an animal39s digestive tract is only one cell thick 0 Tight junctions are in the sheet to make sure no nutrients leak O The tight junctions separate the membrane into two compartments 0 Separates proteins in membrane and keepsthem from drifting fluid mosaic mode Singlecelled organisms also have junctions Cell Structure pt 2 Page 4 CellA 7 7 7 7 Cell B Tight junctions Groups 7 of tight junction proteins Extracellular space Plasma membrane htt sfi uresboundlesscoml18612lar efiqure040603ipe COM M UNICATING MNCTIONS Communicating junctions allow cellsto communicate through diffusion 0 Are called gap junctions in animals 0 Are called plasmodesmata in plants Gap junctions found in both vertebrates and invertebrates O Pannexins proteins in invertebrates O Connexons proteins in vertebrates 0 Open and close in response to Ca2 and H ions Gap junctions create gaps that connect animal cells Gap junctions Membrane proteins from adjacent cells line up to form a channel Figure B1Jbrpa 2 Elalogiull Stlamzre 0 3005 Pearson Prentice Hall Inc I If a cell is damaged Ca2 ionsflow into the cell and closesthe junction and prevents it from spreading Plasmodemata cytoplasmic connectionsthat form acrosstouching plasma membranes 0 Cellcell connection in plants happen only if there are holesin the walls 0 They have a central tubule that connectsthe ER of the two cells Cell Structure pt 2 Page 5 https classconnection sBam azonawscom1 32flashcards1002132jpggap iu nctions1362670294010ipq FNx Central vacuole of cell Plasma membrane Secondary cell wall Primary L cell wall Central K vacuole of cell Middle lamella Cytosol Plasma membrane 39 Plant cell walls L Plasmodesmata htt psssam azonawscom test classconne ction 992 flashcards 324992 ipg pl asm ode sm ataj pg
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