Cell Junctions and extra cellular matrix II

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Cell Junctions and extra cellular matrix II

• chapter 19

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Desmosomes and hemidesmosomes both link to
intermediate filaments
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Cadherins also bind intermediate filaments
together
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Integrins link extracellular matrix to
cytoskeleton
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Size of gap junction channel can be determined
with fluorescent molecules of different sizes
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A Gap junction connexon is made up of 6
transmembrane connexin subunits
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Images of gap junctions
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The permeability of gap junctions can be regulated
dopamine treatment reduces permeability of gap
junctions to a fluorescent dye
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Summary of cell junctions found in the cell
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Summary of cell junctions found in the cell
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In plant cells plasmodesmata perform many of the
same functions as gap junctions
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View of plasmodesmata
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Structure of Cadherin responsible for cell to
cell adhesion in vertebrate cells
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Ca2 is required to establish cell to cell
connection through cadherin
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Three mechanisms that mediate cell-cell adhesion
cadherins
least common
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Cadherins allow cells to sort themselves
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Catenins join cadherins to actin filaments in
adherence junctions
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Summary of junctional and non-junctional adhesive
mechanisms
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Cells surrounded by extracellular matrix
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Cross sectional view of intestinal wall
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Connective tissue underlying the epithelium
contains a variety of cells and extracellular
matrix components
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Fibroblasts surrounded by collagen fibrils
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Glycosaminoglycan (GAG) chains occupy large
amounts of space and form hydrated gels
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Hyaluronan, a simple GAG, occupies a large amount
of space, thereby providing mechanical support
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Repeating disaccharide unit of hyaluronan
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GAG and its core protein form proteoglycan
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Comparison of proteoglycans with a ribonuclease
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picture of aggrecan aggregate, a large
proteoglycan
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structure of Aggrecan aggregate
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Collagen fibril embedded in proteoglycan molecules
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Fibroblast surrounded by collagen fibrils
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Collagen fibrils in tadpole skin
This arrangement is also found in bone and the
cornea
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Elastic fibers in a dogs aorta
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Each elastin protein in the network can expand
and contract as a coil
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Fibronectin is an extracellular protein that
helps cells attach to the matrix
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Connective tissue underlying the epithelium
contains a variety of cells and extracellular
matrix components
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basal lamina in the cornea of a chicks embryo
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A model of the basal lamina
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Cross Section of Kidney
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Filtration is one step in urine formation
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Structure of Nephrons
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Inside Bowmans Capsule
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Basal Lamina plays an important role in filtration