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CytoskeletonThatcher
Thatcher Cytoskeleton Directed Study/Lecture
| Question | Answer |
|---|---|
| Microfilaments | Actin & Myosin |
| Actin | Structural microfilaments, composed of F actin, polarized |
| F Actin | G actins polymerized into a double helix due to ATP hydrolysis |
| G Actin | Monomeric actin subunits |
| Spectrin | Actin crosslinking protein that forms networks in erythrocytes |
| Dystrophin | Actin crosslinking protein that forms networks in striated muscle |
| Duchenne Muscular Dystrophy | Sex linked mutation of the dystrophin gene |
| Myosin | A structural microfilament as well as a motor protein for actin |
| Actomyosin | Actin and myosin associated with each other |
| Stress Fibers | Bundles of actomyosin anchored to the basal surface of fibroblasts, which are attached to the substratum. Produce tension across cell layer. |
| Microtubules | polymers of alpha & beta tubulin |
| Microtubular Associated Proteins (MAPs) | Microtubular crosslinking proteins that form networks |
| What is an important MAPs and what is it connected to? | Tau; alzheimers |
| Intermediate Filaments | Structural components of the cytoskeleton. Complexes composed of proteins that have similar alpha helical cores but distinctive terminal domains. |
| Keratin | A major intermediate filament of epithelial cells. (what hair and nail are mostly made of) |
| Nuclear Lamins | Intermediate filaments supporting the nuclear membrane |
| Collagens | Stracellular matrix fivers that resist stretching; composed of 3 helices coiled around each other in triple helix |
| Elastin | Gtretchable extracellular matrix fibers that provide tissues with pliability |
| Fibrillin | Glycoprotein microfibrils that provide a scaffold for assembly of elastic fibers |
| Glycosaminoglycans | Polysaccharides of the extracellular matrix composed of disaccharide repeats of modified sugars |
| Hyaluronans | A particularly large glycosaminoglycan that exists free in the extracellular membrane |
| Proteoglycans | Extracellular matrix components composed of core proteins attached to one or more glycosaminoglycans |
| Heparin | A regulatory proteoglycan that activates a clotting inhibitor called antithrombin III |
| Laminin | Extracellular matrix crosslinking protein forming networks in the basal lamina |
| Fibronectin | Extracellular matrix crosslinking protein with multiple binding domains for different factors |
| Zonula Occludens (tight junctions) | Thin bands of membrane around the apical perimeters of epithelial cells held closely together by proteins such as occludin and claudin. Seal cells to prevent diffusion of molecules across epithelium. |
| Gap Junctions | Transmembrane complexes that allow diffusion of small molecules between cells to vesicles |
| Zonula Adherens | Rows of structures anchoring actin microfilaments to the apical surface of epithelial cells, just beneath tight junctions |
| Circumferential Belt | Microfilament bundles (actin & myosin)that encircle the apical perimeter of epithelial cells at the level of the belt desmosomes |
| Spot Desmosomes | Isolated "spot welds" joining the intermediate filament cytoskeletons of two cells at lateral surfaces |
| Hemidesmosomes | Structures that anchor the intermediate filament cytoskeleton of an epithelial cell to the basal lamina |
| Focal Adhesions | Structures that anchor microfilament stress fibers to the basal surface of many cells, particularly epithelial cells |
| Membrane-microfilament Binding Proteins | Membrane associated proteins that anchor the microfilament cytoskeleton to the plasma membrane by binding actin crosslinking proteins |
| What are the 3 major classes of cytoskeletons? | Microfilaments, Microtubules, & Intermediate Filaments |
| 5 Examples of Microfilament Mediated Motility | Intracellular membrane trafficking, muscle, contractile ring of cytokinesis, amoeboid motion, and stress fibers |
| Microvilli | Finger like projections of plasma membrane, supported by internal actin bundles, increase plasma membrane surface area for absorption, extremely abundant on brush border of intestinal epithelium |
| Are actins polarized? | Yes positive & negative ends |
| Myosin Assembly | Tetramers made of myosin heavy and light chains. . |
| Myosin Heavy Chains | Made of alpha helical tails and globular heads. Two tails coil around each other to form dimers, this requires ATP hydrolysis. Heads provide motor force. |
| Myosin Light Chains | Serve as regulatory factors controlling contraction of the globular heads |
| Microtubule Assembly | Alpha & Beta tubulins bind to form dimers; bind end to end to form hollow microtubules (polarized). 13 rows per microtubule; alphas face the (-) end and betas face the (+) end. Elongate faster on (+) end. Requires GTP from bera tubulin. |
| 4 Examples of Microtubular Mediated Motility | Intracellular membrane trafficking, mitotic spindle, axonal transport, & flagella/cilia |
| 9+2 Arrangement | Flagella and cilia consist of 9 microtubule doublets with a central microtubule doublet. Dynein arms between doublets create motor force with ATP hydrolysis. |
| Why are intermediate filaments not polarized? | Because they are antiparallel. |
| What is the function of the extracellular matrix? | Provide shape & resiliency to tissues & organs; and a medium for cells to interact with extracellular environment. |
| what are the 4 major compounds of the extracellular matrix? | Collagen, Elastin, Hyaluronan, & Proteoglycans. |
| Is collagen right or left handed? | Left handed due to prolines. |
| What enzyme drives crosslinking? | Lysyl Oxidase |
| Striation | Results from the pattern of overlap between tropocollagens. |
| What are collagens produced by? | Fibroblasts, chondroblasts, and osteoblasts. |
| 4 Collagen Clinical Defects | Fibrosis, Scurvy, Ehlers-Danlos Syndrome, & Osteogenesis Imperfecta |
| What is important in wound healing regarding focal adhesions? | Stress fiber (actomyosin) |
Created by:
htolley
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