BIOL 1111 Lecture 8: BIO: Membranes
21 Mar 2018
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Document Summary
Only on outside - asymmetrical sides (protein distribution is asymmetrical) Variability - number of sugars per chain, sequence of sugars, and branching of chain. Results in cell fingerprint for each individual. Not covered in membrane (ie. hydrogen ions) Carry across membrane (ie. potassium and sodium ions - nerves) Body can recognize invading cells - immune system. Some molecules can pass - some can"t. Proteins are specific to the substance they transport. Diffusion of water across selectively permeable membrane due to a concentration gradient. Greater osmotic pressure, more water in that direction. Moves to area of higher solute concentration. Solute concentration equal in and out of cell. Hypotonic - higher solute concentration inside cell. Animal cells swell and may burst - lysis. Hypertonic - higher solute concentration outside cell. Plant cell shrinks within cell wall - plasmolysis. Movement of polar molecules across non-polar lipid membrane. Moves down concentration gradient - does not require energy.
