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Lecture 13

BIO241 Lecture 13-14

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Jennifer Harris

Tuesday February 24 2009 Degenerative diseasesinfectious diseases as well Beginning this week were going to be talking about cytoskeletal machinery inside cells Next week well talk about cell junctions how cells stick to each other Then the extracellular matrix that surrounds cells how cells stick to this matrixinteract with that matrix Then switch gears to talk about the control of cell numbers looking at the cell cycleprogrammed cell death Looking at mitosiscell divisionhow the control of cell numbers is associated with cancer Finally well touch on how multicellular organisms develop in the last 2 lectures The assigned readings are focused on the topics he covers in lectures Here we have 3 cells that have very different shapes to them These different shapes are linked to the different functions of cells The Goblet cell has a structure to it thats focused on pumping mucus into the lining of our throat and so on Heres the nucleus of this cell in the diagrambasically the rest of the cell is filled with these vesicles that are involved in pumping out this mucus into the extracellular space Compare that to a sperm cell in the middle diagramthis sperm cell has a structure that is made for motility made for swimming The nucleus is at the topthen you have this huge tail at the end further down Photoreceptor cell has the nucleus in the middle On the top are the specific membranes that pick up the photons of light so these are in our eyesthen this light info is then passed through the cell to a synaptic region which then connects to neurons so that we can connect what we see to neurons that link to our brain So each of these 3 cell structures is closely linked to its functionthe cytoskeleton plays an essential role in making these 3 structuresall cell structures Here is an example of microtubules in green reaching outgrabbing onto chromosomes in bluethen theyll pull these chromosomes half of them onto one sidethe other half on the other side to divide the genetic material into 2 cells An example of cellcell interactionshere is a field of cells Inside one of the cells in green are intermediate filaments these are cytoskeletal filamentsthey basically have this network of filaments that are filling up this cell Again you can see the nucleusfilling the cytoplasm we have these intermediate filaments reaching outin blue are cell adhesion complexes that link one cell to its neighbouring cell We can see that as these intermediate filaments reach up to another cell complex there is another set of intermediate filaments in the neighbouring cell that reach outconnect to this onetheyre connect via this cellcell adhesion complex Basically what this makes is a tissuewide protein interaction network so you have this network of intermediate filaments in one cell connected to the network in the neighbouring cell through these cell adhesion complexesby having this network running through this whole tissue it gives the tissue a lot of strength This is what the cells in your skin would look likeit gives them a lot to strength to withstand physical stress
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