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Cell Organization and Motility.doc

8 Pages

Biology (Sci)
Course Code
BIOL 201
Gary Brouhard

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Cell Organization and Motility Cells come in many shapes: Muscles  Bundle of muscle fibres  multinucleated muscle cell  Myofibril  Sarcomere Cells are highly organized structures Muscle cells can morph into short fat cells from being long and cylindrical • Dendrites: signal receiving part of the cell • Axon: sends signal from one place to the other • Different morphologies of cells that are quite similar • Genome of all the cells are the same (have all the same DNA) How is it that all these cells with same DNA differentiate? Cells are internally organized Two domains: Apical domain (sees the inside/lumen of intestine) Basolateral makes connection with extracellular matrix. Cells have the ability to import and export cargo Cells can migrate into wounds – not only bacteria that can move around, but cells within our own body can migrate. Movement of cells is for healthy physiology/function of cell Also prevalent in disease, metastasizing cells crawling into the body, punching through epithelial cells Cell constructs a cytoskeleton that shapes it just like our skeleton shapes us. They make small building blocks that are able to self-assemble. Key role in cell physiology The Cytoskeleton plays a key role in cell physiology and metabolism Shape, structure and stability Intracellular transport Contractility (eg: muscle) and motility Spatial organization (apical versus basolateral domains) Microfilaments -made of actin monomers, polymerize -two-stranded helical structure -discovered first Microtubules -ab-tubulin dimer -hollow tubes -play role in structure of cells because stiffer -longer protofilament structures (13 of them form hollow tube) -can be considered as one unit Intermediate filaments -formation of nuclear lamina - gives nucleus mechanical structure -huge number of diseases associated with laminothopies. Cytoskeleton: Polymers 1 Microtubules = Poles Very stiff 2 Resistant to compression; - large, rigid, hollow tubes. like plexi-glass, will not buckle under a lot of compression, resistant to compression 3 4 Actin Filaments = Wires, High tensile strength 5 But flexible; - if you pull from both ends, won't break; flexible 6 Intermediate Filaments = Ropes, Elastic and flexible; if you pull on them, they stretch, they have the ability to slide relative to one another 7 Cytoskeleton similar to scaffold at a construction site (loose analogy) Actin is an ATPase that drives cell motility. It was discovered in 1942 by Bruno Straub, a Hungarian biochemist. -has ATP-binding cleft -spend ATP by polymerizing actin -if translocate a cell across a distance -- it takes energy/work -the energy comes from ATP hydrolysis of actin. -actin first purified from muscle tissue -actin -
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