BIOL130 Lecture Notes - Lecture 1: Loose Connective Tissue, Tight Junction, Dietary Fiber
20 Apr 2017
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Extracellular matrix/ cell wall common features: cross linked network of filaments, resists stretching and straining forces. Plant cells have rigid cell walls: plants are sedentary, tissues rigid, cells weak and fragile if separated from their walls (called protoplasts, have no intermediate filaments, plant cell wall is an extracellular matrix secreted by the plant cell. Primary and secondary plant cell walls: primary cell wall laid down first, secreted as cells are growing, relatively thin compared to secondary wall, cellulose microfibrils form network filled in by gel-forming pectins. Cellulose fibres plant indigestible poly saccharide dietary fibre the rebar of the cell. Pectin (soft concrete) the filler: secondary thick layer because primary laid down first, secondary will push the layer further out. If the (cid:272)ell(cid:859)s pla(cid:374) is to gro(cid:449) do not lay the secondary cell wall: much ticker than the primary becomes rigid, found only in certain cell types as they mature. The force of cellulose synthesis drives the movement of the complexes.
