BIOL 341 Lecture Notes - Lecture 16: Microfibril, Middle Lamella, Cellobiose
6 Mar 2017
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Document Summary
Extensible and able to incorporate new structural material. Encased by the middle lamella (which is the real first cell wall) Usually for strength (e. g. gravity, -ve pressure transpiration) May be highly specialized, e. g. xylem vessels and phloem cells. Cell wall components (relative amounts differ: cell type / species / development) Synthesized by golgi membrane glycosyltransferases: hemicellulose (hc): heterogenous polysaccharides. Link cellulose microfibril: pectin (mostly in 1 walls): heterogeneous polysaccharides, hydrated gel matrix linked by ca2+ bridges, most important for hydration, prevents aggregation/collapse of cellulose network. Strength (e. g. tracheids, xylem vessels), allows for upward growth. All other molecules are pectin forming gelatinous substance. Getting energy from the starches, sugars, oils that you find naturally in those plants: biodiesel, biogas, bioalcohols (e. g. fermentation to ethanol) Using cell wall material (lignocellulosic biofuel: we want the sugar: cellulose, hemicellulose = good, we don"t a(cid:272)tually want the non-sugars: lignin = bad. Thermo-chemical and biochemical (enzymatic) processing required to release sugars from cellulose prior to fermentation.
