Questions Describe the structure of a focal adhesion, Adherins Junction, hemidesmosome and desmosome. ●Adherens Junction- ● Focal Adhesions and hemidesmosomes are created from integrins ● Focal Adhesion - cell to matrix junction linking extracellular proteins to actin filaments, composed of integrins ● Hemidesmosomes- i t is a cell to matrix linkage that is composed of integrins that links extracellular matrix proteins to intermediate filaments Pick any tissue you want and describe the following: ● 3 cell types found ● how each cell contributes to the function ● cell- cell junctions or cell to matrix? ● which cell type is the major contributer Epithelial tissues /skin contain fibroblasts, immune cells, and endothelial tissues. Fibroblast makes ECM. Immune cells help to protect these cells from infection and endothelial cells bring proteins oxygen and other essential molecules needed for function. Because epithelial tissues are a barrier to foreign bodies, it would be composed mostly of cell to cell junctions to prevent pathogens from entering. Basal Membranes- Basal membranes that are not intact tend to have higher rates of metastasis. Basal membranes act as a barrier taht protects harmful cells from spreading into the bloodstream. Proteasess that degrade the basal membrane can lead to metastasi s Explain the difference b/w necrosis and apoptosis. Necrosis Apoptosis ● cell death due to mechanical stress/ rupture ● abnormal and harmful to cells, organelles may not be intact/ cannot be recycled ● random, proteins and eveything is expelled into the extracelular space ● programmed cell death ● can be healthy, organellese remain intact and can be recycled ● involves caspases ● compartmentalized controlled cell death
Activation of integrins slows down the cell during movement. explain why. ● Cells use integrins to move by turning them on and off. ● Cell movement is caused by integrins on the front of the cell turning on and integrins on the back of the cell being turned off to release the cell and allow the cell to crawl ● integrins that remain adhered would offer resistance to cell movement and thus slow it down Identify which cytoskeletonal proteins are denoted. Which is the weakest? Whichj proteins resist compression and which resist tension? ● Intermeidate filaments- are the strongest and the most flexible, resist tension ● Microtubules- are much more rigid and fail britally; they resist compressive forces and are the weakest because they can withstand the least stress ● Actin- not as weak and resist tensile loads How do kinesin, dyamin, and myosin contribute to mitosis? Kinesin Dyamin Myosin ● Help the cell grow ● dyamin helps transport materials away from the MTOC to the + end; ● thus seperating the chromosomes ●
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- Spring '14