Flashcards
ECM-zena
Flashcards do conjunto (21)
- 1what is the extracellular matrix formed of?cells and a space filled with a network of macromoleules
- 2what are the 2 types of animal tissue organisationepithelial tissues- sheets of tightly bound cells, cell-cell adhesions inked to cytoskelton, thin layer of ECM
connective tissues - rich in ECM compoents(eg collagen fibres), few cells few cell:cell adheions, cell-matric adhesions important - 3what do connective tissues do?provide routes of communication and supply, eg blood vessels nerves
in connective tissues ECM determines the tissues physcial properites - 4name 5 types of connective tissuetendon- ropelike, high tensile strength (collagen fibres)
blood vessel walls, ressilaint, flexible (elastic fibres)
cartilage- tesnile strength and elastic properties (collagen and proteoglycan)
bone- rigid, incompressible (calcified collagen )
vitreous conent of the eye - transparent jelly (collagen fibres and hyaluronan - 52 main types of component in ECM1)glycosaminoglycan polysaccharide chains (GAGs)
eg. herapin sulphate, hyaluronan (usually covalentally linked to proteins)
2) fibrous proteins
eg collagen, fibrillim, elastin, laminin - 6Also adhesive glycoproteins which act as adapters, providing molecular interactions by binding matrix proteins, cells or both True or falsetrue
- 7Give me some facts about GAGs-unbranched polysaccharide chains composed of repeating disaccharide units
-one of 2 sugars is always an amino acid
-• second sugar usually a uronic acid (glucuronic or iduronic)
• highly negatively charged (sulphate and carboxyl groups - 8what are the 4 main groups of GAGshyaluronan
chondoitin sulphate and dermatan sulphate
- heparan sulphate
- keratan sulphate - 9proteoglycan synthesistranslocated into ER -> linker added by glycosyl transferase in ER/golgi ->polysaccharide elongated by glycosyl trasnferase in golgi -> modification eg epimerisation sulphation in golgi
- 10collagenalpha chains form trimers- each chain folds ina helix with 3 amino acids/turn--> wrap around each other to form tightly packed triple helical rod
- 11what can collagen trimer form?fibrils.
self assemble into fibrils --> covalent crosslinks form between lysines and hydroxylysines
collagen fibrils bundle into fibres - 12sysnthesis and assembly of collagensyntheiss of pro-alpha chain -> hydroxylation of selected proline and lysines ->glycosylation of selected hydroxylysines -> self assembly of 3 pro-alpha chains ->procollagen tripe helix formation -> secretion ->cleavge of properties -> self assembly into fibril
- 13main component of elastinhydrophobic protein
secreted as tropoelastin, then highly crosslinked to form network of fibres and sheets
• elastic fibres also covered in microfibrils – made from other glycoproteins e.g. fibrillin - 14role of fibroconectinhelp attach cells to ECM
- 15fibroconnectin structure• fibronectin forms dimers (usually heterodimers – differential splicing)
• each subunit comprises multiple functionally distinct domains and repeated modules (e.g. type III fibronectin repeat) – different adhesive functions
• can also form insoluble, crosslinked fibrils - only when binding cells and subject to tension - 16basal lamina• the basal lamina is a very thin, tough, flexible sheet of ECM
• essential mechanical role e.g. connecting epidermis to dermis
• underlies epithelia, surrounds muscle and nerve cells - 17lamin structure• heterotrimer of a, b, g chains (multiple isoforms of each)
• multiple binding sites for other components and cells
• assembles into network via heads - 18how is the ECM organisedfibroblasts, chondroblasts (cartilage), osteoblasts (bone) secrete and assemble ECM components (e.g. collagen fibrils) bind ECM components and apply tension via integrins and cytoskeleton (e.g. formation of fibronectin fibrils)
can orientate ECM - 19Remodelling/degradation of the ECMoccurs during:
- normal tissue development
- wound healing
- bone remodelling
- cell migration e.g. inflammation (for white blood cells to infiltrate tissues), tumour cell invasion and metastasis - 20ECM remodelling carried out by• carried out by cellular proteases:
- matrix metalloproteases (MMPs) e.g. MMP-9 (collagenase)
- serine proteases e.g. Urokinase or uPA
• activity confined to cells by:
- local activation from inactive precursors
- cell surface localisation e.g. MMP-14
- inhibitors e.g. TIMPs, serpins - 21Roles of the ECM• structural integrity of connective tissues
• scaffold for cells
• reservoir for growth factors and cytokines
• provides pathways for cell migration
• regulates cell shape, polarity, survival, proliferation and function
• regulates tissue development
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- FlashCards sobre ECM-zena, criado por Zena Dodds em 06-12-2017.
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- Zena Dodds
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