Biology 2581B Study Guide - Quiz Guide: Cell Wall, Middle Lamella, The Plant Cell
2 May 2020
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Document Summary
It is composed of the following parts: cellulose microfibrils: bundles of cellulose that give the primary cell wall tensile strength. They are arranged in lamellae (layers): cross linking glycans/hemicelluloses: are attached to the cellulose microfibrils by hydrogen bonds with their sugar backbone. They cross-link the lamellae and are arranged in a complex network: pectin: in the primary cell wall, pectin polysaccharides form a matrix in which the cross- linked cellulose network is embedded. Pectins are a heterogeneous group of branched polysaccharides with a negative charge, which makes them highly hydrated and associated with a cloud of cations, forming a gel like structure. They are said to hold different cell wall compartments together, mainly in the middle lamella (sticky layer to hold adjacent cell walls together): lignins: secondary cell walls contain lignin to make them waterproof, hard and woody. The fluid contained in the walls surrounding a plant cell is called the aqueous extracellular environment.
