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BI220 E1 L45
lecture 4&5 slides
| Question | Answer |
|---|---|
| cytoskeleton | complex fiber network. cell structure, facilitating motility, mediating intracellular transport of materials |
| dynamic instability | constant assembly and disassembly - changes cell structure and function |
| intermediate filament protein examples | keratin (cytoplasmic, epithelial cells). vimentin, desmin (cytoplasmic, connective tissue & muscles). neurofilaments, nestin (cytoplasmic, neurons). lamins (nuclei of animal cells). |
| plectins | protein class - crosslink & connect all 3 main components of cytoskeleton |
| intermediate filaments function | provide mechanical strength to cells, resist stretching forces, form scaffold structure in cells for anchoring cytoskeleton. NO MOTILITY |
| epidemolysis bullosa (EB) | butterfly skin - connective tissue disorder causing blistering of the skin due to minimal touch |
| EB cause | issues with anchoring between epidermis & dermis. often caused by mutations in keratin or plectin |
| nuclear lamina | responsible for assembly & disassembly of nucleus during cell division. composed of lamins forming meshwork of the inner membrane |
| progeria (HGPS) | premature aging due to point mutation in LMNA gene = failure to produce lamin A. cell division greatly limited --> premature aging --> death. |
| cell structures comprised of microtubules | centrioles, centrosomes, mitotic spindle fibers, flagella, cilia |
| microtubules key roles | intracellular trafficking, organelle positioning, cell locomotion (cilia, flagella), nuclear division, structural support |
| microtubules composed of? | tubulin dimers (alpha & beta monomers) |
| plus end of microtubules | exposed beta monomers (faster addition as tube grows) |
| minus end of microtubules | exposed alpha monomers (slower addition as tube grows) |
| MTOC | microtubule formation site |
| MTOC functions | 1. organize microtubules for motility structures (flagella, cilia) 2. organize mitotic spindle during cell div |
| gamma tubulin rings | nucleation sites for building new microtubules |
| MTOC structure | centrosome. inside are 2 centrioles. made of 9 sets of microtubule triplets. surrounded by pericentriolar material (PCM). |
| PCM contains | gamma-tubulin, pericentrin, ninein. |
| GTP | guanosine triphosphate. energy source for polymerization of microtubules |
| capping proteins | prevent changes to structure and length of microtubules. centrosome & MTOCs cap - end. membrane-associated proteins cap + end. |
| cell polarization | capping microtubules on one end. creates distinct poles of the cell |
| microtubule motor proteins | intracellular transport of substances |
| anterograde motion | movement of substances AWAY from cell nucleus. typically involves motion toward + end of microtubules |
| retrograde motion | movement of substances TOWARD cell nucleus. typically involves motion toward - end of microtubules |
| dyneins | microtubule motor protein. - end of microtubule. retrograde |
| kinesins | microtubule motor protein. + end of microtubule. anterograde |
| head portion of motor protein | ATPase activity - utilizes ATP to facilitate motion via ATP hydrolysis & binds to microtubules |
| tail portion of motor protein | binds specific cargo |
| motor protein cargo examples | proteins, vesicles, organelles |
| how do motor proteins cause motion? | proteins (i.e. dynein) apply forces on cross linked microtubules, causing bending & thus motion |
| microfilament-associated cell processes | chemotaxis, phago/pinocytosis, microvilli, stress fiber formation, lamelli/filopodia, cleavage furrow / contractile ring |
| motor proteins that provide pulling forces within cell | actin & myosin |
| treadmilling | adding subunits at barbed end & losing subunits at pointed end --> no net change in length |
| ATP bound actin polymerizes at ____ end | + |
| ATP hydrolyzed to ADP effect | actin monomers become more fragile --> more likely dissociate from - end |
| amoeboid movement | extending a portion of plasma membrane & forming contact & pulling cell forward |
| pseudopodia aspects | lamellipodia (flattened extension) & filopodia (pointy extension) |
| myosin does ________ | contractile forces for pulling |
| myosin | bind to and "walk" along microfilaments toward + end of structures, consuming ATP. carries loads (i.e. vesicles) like dyneins and kinesins on microtubules. myosin i & ii are common in humans |
| sliding filament theory | actin & myosin are responsible for forces generated. filaments slide against one another |
| myosin | thick filament |
| actin | thin filament. contains 2 types of bound proteins which are important in contraction |
| tropomyosin | cable which covers myosin binding sites |
| troponin | calcium binding molecule, causes change in tropomyosin position |
| rigor mortis cause | lack of ATP - locking actin & myosin |
Created by:
knorrod
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