Biology Week 2/10/16
Biology Week 2/10/16 20146
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This 2 page Class Notes was uploaded by email@example.com Notetaker on Monday February 15, 2016. The Class Notes belongs to 20146 at Indiana University of Pennsylvania taught by Robert Major in Spring 2016. Since its upload, it has received 9 views. For similar materials see Principles of Cellular and Molecular Biology in Biology at Indiana University of Pennsylvania.
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Date Created: 02/15/16
Week of 2-11-16 Thursday Membrane Transport 1) Some substances can diffuse through membranes. a. Small, non-polar, non-charged b. O ,2CO ,2N ,2steroid hormones i. Very fatty 2) Some substances do not diffuse. a. Larger, polar, charged b. H , Na , K , CO 2+,Cl , Mg2+ 3) Charged ions are not evenly distributed across a membrane. a. Extra cellular (outside) i. Na ii. Cl- 2+ iii. Ca b. Intra cellular (inside) i. K+ c. Extra and intra are separated by plasma membrane 4) Proteins within a membrane can affect movement. a. Channel proteins. b. Passive transport: Ions move passively down a concentration gradient i. No input of energy 5) Movement of Solute a. If the concentration is higher on one side, movement will move to the other side. b. Membrane potential: difference in charge across the membrane i. Affects solute movement ii. Cytosolic side of the plasma membrane is usually more negative than the extra cellular c. Going in the opposite direction, positive extracellular side will not help positive solutes through. i. Net driving force for movement is not as strong ii. Electrochemical gradient: net and driving force 6) Building up concentration of an ion on one side a. Ions are actively pumped against their gradient i. Active transport: input of energy required b. Hypertonic: solute concentration is higher on this side c. Hypotonic: solute concentration is lower on this side d. Isotonic: solute concentration is the same 7) Water Movement a. Solute concentration will affect water movement b. Aquaporins: specialized channels that allow water to pass through c. Osmosis: movement of water down its concentration gradient from low to high i. Solute Concentration high water concentration is low ii. Solute Concentration low water concentration is high Transporters 1) Transporters can be “passive.” a. Concentration gradient determines direction of movement i. Movement can occur in both directions b. Conformational change occurs 2) Transporters can also be “active.” a. Pumps: require energy (ATP) i. Can be coupled together b. Na /K ATPhase i. active transporter pump c. coupled: pumps work in twos i. doesn’t use ATP ii. couples an unfavorable transporter to a favorable transporter in order to drive the reaction iii. Na+ and glucose ride through together d. Symport: transport occurs in the same direction e. Antiport: transport occurs in opposite direction Channels 1) Channels are closed until they are “told” to open. a. Gated: open and closed b. Voltage gated: open in response to a voltage change at the membrane c. Ligand gated: open in response to a ligand binding to the channels 2) Nerve Cell (Neuron) Signaling a. Axon: connects cell body to terminals b. Action potential: traveling wave of excitation/nerve impulse c. Ions are asymmetrically localized near a membrane. i. At rest, membrane is polarized ii. Resting member potential: outside of cell is more positive when compared to the cytosol d. Synapse: point where the neuron signals to another cell i. Neurotransmitters activate the postsynaptic cell
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