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BIO 1201Test 2 SG

BIO 1201Test 2 SG - Biology 1201 Section 1 Examination Two...

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Biology 1201 Section 1 Examination Two Thursday, March 6 at 6:00 PM in Campbell Auditorium Bring your LSUID and a number two pencil. I'll provide the questions and a scantron. 52 questions = 104 points Membranes and membrane function 8 Questions How are membranes adjusted for different temperatures? Increased saturated fats increased the fluidity of the membrane At cold temperatures unsaturated fats would increase Transport of materials across the membrane Biological membranes are made of proteins and phospholipids. What types of molecules can move across the membrane? Simple diffusion No energy and no carrier molecule Facilitated diffusion No energy but yes carrier molecule Active Transport against the concentration gradient requires supplied energy (ATP) Tonicity and aquatic organisms - from lecture Marine Invertebrates & Marine Elasmobranch Fishes Isotonic with seawater Freshwater Bony Fishes Hypertonic to freshwater Gain water Marine Bony Fishes Hypotonic to seawater Lose water Hyper-, hypo- and isotonic Hypertonic -lower water potential -more solutes dissolved in it -tend to gain water Hypotonic -higher water potential -fewer solutes dissolved -tend to lose water -Plants need a hypotonic environment Isotonic -equivalent water potentials -equal number of solutes dissolved -no net movement of water -Animal cells needs to be in an isotonic environment Osmosis and the direction of net water movement Figures 7.2, 7.3, 7.5, 7.11, 7.13 , 7.17 Enzymes 7 questions Function of enzymes •Enzymes lower activation energy barrier How they work 1
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Do not reverse an energetically unfavorable reaction Each step has a specific enzyme Cannot run out Coenzymes Inhibition (Figures 8.17, 8.19, 8.20 and 8.21) Competitive, Noncompetitive, Allosteric, Feedback Competitive enzyme inhibition Substrate and inhibitor compete for binding to the active site of the enzyme Inhibitor is structurally similar to the substrate NOT identical Noncompetitive Enzyme Inhibition Inhibitor binds at a site away from the substrate binding site Causes an conformational change in the enzyme Not overcome by increasing the substrate Allosteric Enzyme Regulation “Other site” Modulator (activator or inhibitor) binds to a site other than the substrate binding site (active site) Causes a conformational change in the enzyme which changes the activity Circe Effect Luring of substrate into active site of enzyme Positively charged argenine side chain lowers the negatively charged metabolite into the active site Metabolic Pathway regulation Chemical transformations in small steps Each step catalyzed by a specific enzyme How is the pathway turned off? (1 st enzyme) Allosteric inhibition of the 1 st step Feedback inhibition by the end product of the pathway Stability of biological molecules
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