BIOL 1107 1nd Edition Lecture 8 Outline of Last Lecture I Starch II Cell Identity III Fats Steroids and Phospholipids Outline of Current Lecture I Phospholipid Bilayer a Movement across membrane b Bend in tails II Concentration Current Lecture I Phospholipid Bilayer a Movement across membrane Things will not readily move across the phospholipid bilayer unless they are really small have a hydrophilic hydrophobic region that can interact with the bilayer or are being assisted o readily movement means that items cross without being facilitated or actively transported O2 CO2 and N2 small nonpolar molecules can readily move through bilayer if they have enough kinetic energy and if the concentration gradient is favorable A favorable gradient means that the concentration within the cell is different than that outside of the cell H2O small uncharged polar molecules readily moves through membrane due to the concentration gradient Movement is facilitated by channels aqua pores that assist in the movement of water Glucose large uncharged polar molecules does not readily get through the membrane In order for glucose to pass through movement has to be facilitated Cl K and Na ions does not readily get through membrane because they have a potential charge causing ions to interact with the surface of the membrane and be repelled Movement must be facilitated These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Cystic Fibrosis is when tissue and organs do not have the ability to build chloride channels into the membrane b Permanent bend in tails of phospholipids increases permeability Unsaturated hydrocarbon chains have at least one double bond Saturated hydrocarbon chains have single bonds are without doublebonds The more kinks in the tails the more unsaturated the lipid becomes The kink has to do with a double bond between the bottom and top of the lipid creating a stronger pull II Concentration If cells remain in equilibrium they will die The concentration outside of the cell is different than that inside the cell o Outside solution with a higher concentration is hypertonic to the inside of the cell o A solution with a lower concentration is hypotonic to the cell o If solute concentrations are equal on the inside and outside of the cell the solutions are isotonic to each other Integral proteins are amphipathic spanning the membrane forming channels An electrochemical gradient is due to a difference in both the concentration and the charge It is important to note that concentration and charge are two different gradients that together form the electrochemical gradient
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