biol 201 notes - Actin filaments : Formin : Poles:...

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Actin filaments : Formin : Poles: microtubules Wires: Actin filaments Microtubules: 13 proto-filaments in total. Initially in plant cells, but then in animal cells. Plant cells and animal cells have basic organelle structure. Why do Cells need microtubules? Very tiny. Persistence length is one millimeter. Microtuibule organizing center, the centrosome. Cilia are bundles of microtubules. They push things out of the lungs. Smoking would cause cilia to integrate. Severe coughing is caused by cilia regrowth in the lungs. Flagella: sperm has flagella. clamidemoses in sperm contains the flagella. 9 doublets surrounds 2 singlets in the middle. Chemotherapy targets. Tubulin: alpha tubulin and beta tubulin, dimer. Functionally building block of the microtubule. Alpha and beta tubulin organized linearly to form one protofilament, 13 profilaments forms a microtubule. There’s a seam in the middle. Critical concentration: concentration above which the concentration would grow. There’s no fixed concentration for microtubule because they are not as well known as actin. GTP tubulin forms stable polymer. Likes to be in polymer, likes to be in tube. GDP doesn’t like to be in polymer, wants to get out, it is kinked. In a catastrophe, the microtubule collapse. Dynamic instability: GTP cap keeps the whole polymer stable. -Microtubule-Associated Proteins Microtubule organizing center: centrosome in animal cells. microtubule negative ends are embedded in it. Plus ends are in the cytoplasm. Centrosomes: mother centriole and daughter centriole. Pericentriolar material: whatever things that surrounds the centrioles. Microtubule nucleation factor: gama-TURC. It has red disks. Nucleation is very slow. Microtubule-severing enzymes: catanin, it cuts microtubule. Plus-TIP proteins: located at the plus end of the microtubule. EGFP-EB1 (end binding protein 1). Works as a marker to see the plus ends of microtubule. CH domains: caponin-homology domains, binds only the plus ends of the microtubule. Recognizes the GTPs. Other plus TIPs hitch a ride on EB1.
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Depolymerases: kinesin 13 family proteins, which are part of the kinesin proteins. They break down physically the ladder by using energy of ATP. Stathmin grabs four tubulin in solution and not letting them get out, keeping the tubulin not able to stick back on to the microtubule. MCAK: a kind of kinesin 13 protein. The control filament has a blunt end. But, when +MCAK is added, the end becomes open. Polymerases: microtubule polymerase act like RNA polymerase. as concentration of tubulin increases, growth rate increases. Growth rate as a function of concentration. XMAP215 increases K on of tubulin by factor of 5. XMAP 215 binds to tubulin. All of the polymerases act by the same principle. Binds to monomer, and stick them together. Add tubulin to the end of microtubule. RNA polymerase, DNA polymerase, formin act the same way. It’s like a catalyst. Catalyze both the forward reaction and reverse reaction. Catalyzes the reverse reaction. Chimography. Putting a movie into an image. The
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This note was uploaded on 09/18/2011 for the course SCIENCE biol 200 taught by Professor Bureau during the Spring '11 term at McGill.

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biol 201 notes - Actin filaments : Formin : Poles:...

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