-
what shapes the three dimensional organization of tissues?
cell cell and cell-matrix interactions; every cell has unique architecture particular to cell type
-
what are the 5 major groups of proteins of ECM?
- collagens (most abundant)
- elastin (contain glycoproteins)
- proteoglycans (specific sugar groups)
- hyaluronan
- adhesive glycoproteins
-
why does distinct cell types secret a variety of ECM proteins and in differing proportions?
EMC in distinct tissues is specialized for particular functional needs (tendons, blood vessel walls)
-
where are networks of collagen most commonly found?
basal laminae, that underlie epithelia, required for polarization
-
how are collagen fibers organized?
single collagen polypeptide chain, triple stranded collagen molecule, collagen fibril and collagen fibers
-
describe the molecular structure of collagen molecules
- rod shaped, triple helices, contain series of triplet sequence (Gly-X-Y)
- X is commonly proline, Y hydroxyproline
- consists of three left handed helices, form a larger helix, packing glycines at the center
- 25% vertebrate body weight
-
when can cells order the collagen network?
after it is secreted
-
what is a main component of connective tissue?
collagen
-
what is the most abundant protein in mammals?
collagen (25-35% of whole body protein content)
-
what is the shape of collagen and where is it commonly found?
- in the form of elongated fibrils, it is mostly found in fibrous tissues such as tendon, liagment, and skin, cornea, cartilage, bone, blood vessels, the gut and intervertebral disc
- elastic and bendable with mechanical properties
-
what produces fibrillar collagen?
fibroblasts
-
what kind of collagen is found in tendons, bones and connective tissue?
provide tensile strength
-
what are the different isoforms of collagen, how are they different?
fibrillar, sheet forming, anchoring/linking; vary in size and shape according to their function
-
what is the role of protein disulfide isomerase in collagen biosynthesis?
- folding of collagen via the formation of globular structure on the COOH ends, which ensures
- 1)correct selection of alpha-chains
- 2)aligns 3 polypeptides with their C terminal Gly-X-Y repeats in register
- 3)prevents pre-mature assembly of fibrils during transit through Golgi network
-
what is the funciton of prolylpeptide isomerase?
catalyzes the interconversion of trans-proline peptide bonds
-
what is the role of procollagen proteases?
work to cleave pro-peptides, allowing collagen to self assemble into fibrils
-
what type is the sheet-forming collagen?
- polymerize into sheets that surround organs and tissues
- type 4 collagen is mostly commonly found in basal lamina
-
what kind of collagen organization does cornea and bone have?
alternating, plywood-type organization, going in different directions provides strength and elasticity
-
what kind of collagen organization does tendons have?
long parallel bundles along the axis of tension; strong and resists deformation
-
what kind of fibrils are found in the cartilage?
smaller, randomly oriented fibrils.
-
where is the network of collagen found?
in basal lamina, underlying epithelial cells.
-
where is the wickerwork organization found in cells?
skin
-
how are bones formed?
collagen is secreted by osteoblasts and mineralization occurs by calcium phosphate deposition
-
how are concentric rings observed in bone?
generate by perpendicular deposition of collagen fibers
-
what gives the elastic characteristic to cartilage?
fibers are embedded in a hydrate network of proteoglycans (sugar) and glycosaminoglycans
-
what is the role of linking collagen?
link fibrillar and sheet forming collagens to other structures most anchoring fibrils are type 7 collagen
-
what are blisters caused by?
mutations in type 7 collagen that causes the epithelium to pull away from underlying connective tissue
-
what is a key component of elastic fibers?
fibrillin
-
what are elastic fibers?
- rubber lack found in connective tissue of the skin, walls of arteries and the lung
- recoil passively after tissues have been stretched
- network of fibrillin microfibrils, embedded in a core of cross linked elastin proteins
- produced by fibroblasts
-
what are tropoelastins?
elastin subunits, crosslinking of elastin molecules yields a ring structure that covalently corss links tropoelastins to each other
-
what are GAGs and proteoglycans?
long polysaccharides made up of repeating disaccharide units
-
what are the major components of cartilage, loose connective tissue and basement membranes?
proteoglycans
|
|
