Lecture 3 Flashcards

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1
Q

What are the three types of intercellular junctions ? Describe them

A

1) Tight junctions : create epithelia, prevent leakage of fluid, ions, … (watertight). Protein complex = occludin, claudin 1

2) Desmosomes (anchoring junctions) : on lateral side of membranes -> adhesion protein (cadherin) connected to cytoskeleton bridges the space between the cells -> strong mechanical attachment

3) Gap junctions : assembly of 6 proteins connexins creates a connexon with a gap in the middle -> communication through exchange of materials (selective)

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2
Q

What are the two types of ECM ?

A

Intersititial matrix and basement membrane

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3
Q

Describe intersitial matrix : where, composition

A

In connective tissue, synthesized by mesenchymal cells, forms amorphous gel structure.
Collagen, fibronectin, elastin, proteoglycan, hyaluronate, …

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4
Q

Describe basement membrane : where, composition

A

Highly organized around epithelial cells, endothelial cells and smooth muscle cells.
Synthesized by mesenchymal and epithelial cells.
Porous flat lamellar mesh.
Collagen IV, laminin, sulfated proteoglycans.

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5
Q

4 main functions of ECM

A

1) mechanical / structural support
2) control of cell proliferation (growth factors and cytokines)
3) scaffolding for tissue renewal
4) establishement of tissue microenvironments

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6
Q

What are the three groups of proteins composing ECM ? fourth ?

A

1) fibrous structural proteins : collagen, elastins, fibrillin -> tensile strength and elasticity
2) Water-hydrated gels (proteoglycans) -> compressive resistance and lubrication
3) adhesive glycoproteins and receptors : fibronectin, laminin and integrin -> connect ECM and cells
4) water

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7
Q

structure of collagen

A

amino acids in form of triple helices (3 alpha chains) -> fibrils -> fibers

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8
Q

role of integrin ?

A

link ECM to cytoskeleton (creates focal adhesion complexes) and initiate intracellular signaling cascades

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9
Q

Different things that adhesion can influence

A

1) cell shape : cell can spread depending on the nb of focal adhesions
2) cell proliferation
3) cell migration
4) differentiation (depending on what is secreted / produced in the ECM)

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10
Q

What happens if we have no vitamin C ?

A

Problem in collagen production -> scurvy : poor vessel suuport, impaired wound healing, …

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11
Q

What is the result of a collagen I defficiency ?

A

osteogenesis imperfecta : brittle bones, short height, …

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12
Q
A
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