BIOL123 Lecture Notes - Lecture 8: Cell Membrane, Extracellular Fluid, Glycocalyx
Document Summary
Cell membrane: boundary between extracellular fluid and cytoplasm, plasma membrane separates the cell from its environment, selectively permeable, fluid mosaic model, phospholipid bi-layer. Ion exchange, nutrient entry, & waste removal: sensitivity to the environment communication, extracellular fluid composition, chemical signals, structural support connections and stability. Lecture 8/9: membrane structure diffusion and osmosis: attachment: cell to cell; cell to base of support. Selective permeability: control entry and exit of all substances, (cid:862)regulate (cid:272)ell"s (cid:373)ole(cid:272)ular traffi(cid:272)(cid:863, regulate internal environment, homeostasis, responding to ever-changing needs, movement depends on substance, size, charge, shape. Passive transport: driving force is random movement of molecules, more movement of molecules from high to low concentration, therefore, tendency for concentration to become uniform, molecules appear to always move down a concentration gradient. The movement of molecules from regions of high concentration to low concentration across the: uncharged molecules can freely pass through the bi-layer concentration gradient.
