BIOL 118 Lecture Notes - Lecture 3: Cell Wall, Ground Substance, Microfibril
18 Feb 2017
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Unicellular organisms must sense and respond to their environments. Multicellular organisms" cells must communicate, cooperate, and respond to each other. Extracellular layer: fibrous layer that is embedded in a stiffer ground substance, helps define cell shape, helps cell attach to each other, protection of the cell. Plant cell wall: a primary cell wall, long strands of cellulose bundled into microfibril filaments, form a crisscrossed network, the network formed is filled with pectin, a gelatinous polysaccharide, prevents the cell from bursting by osmosis. High solute concentration in the cell: water enters the cell. Animals cells secrete an "extracellular matrix: the ecm consists of. A gelatinous polysaccharide as ground substance called proteoglycan. Collagen: most common ecm protein fiber; is flexible and made of 3 chains that wind around each other. Laminin: cross-links the ecm together, shaped like a t and has arms that move around a little. Integrins: transmembrane proteins, bind to ecm proteins on the outside of the cell.
