My_Ch6_lecture(2009030423450924)

My_Ch6_lecture(2009030423450924) - Chapter 6 Metabolism...

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Chapter 6: Metabolism Purpose : to understand that metabolic pathways involve energy transformation, and how enzymes work (AP Bio Major Themes 3: Energy Transfer, 5: Structure and Function, 6: Regulation). What you MUST know from Chapter 6: Anabolic vs. catabolic reactions Free energy Endergonic vs. exergonic reactions ATP Enzymes Regulation of enzymes Allosteric enzymes Metabolism —all of an organism’s chemical reactions, which manage the material and energy needs of a cell Catabolic pathways (catabolism) break down complex molecules to simpler molecules o “downhill” reactions→energy is released .... to drive anabolic pathways o example: cellular respiration breaks down glucose Anabolic pathways (anabolism, synthesis) form complex molecules from simpler molecules o “uphill” reactions→energy is used to run the reaction o example: photosynthesis makes glucose
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Bioenergetics —the study of how organisms manage their energy resources (metabolism). Organisms transform energy (change it from 1 form to another) example: chemical energy (glucose) is transformed into kinetic energy (when you move your muscles) Some quick, EASY physics as it relates to living things. You do NOT need to be a physicist to understand this! Energy —the capacity to do work, to move matter against opposing forces (gravity, friction) Kinetic energy —energy of movement o Heat (thermal energy)—kinetic energy of random movement of molecules Potential energy —stored energy that can be used at some future time to do work Thermodynamics —the study of energy transformations Closed system —the subject of study (energy) is isolated from its surroundings Open system —the subject of study (energy) can freely move between the system and the surroundings First Law of Thermodynamics o Energy can be transferred and transformed, but it cannot be created nor destroyed o = conservation of energy o The total quantity of energy remains the same (in the universe) 2 nd Law of Thermodynamics
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o Every energy transfer or transformation increases the entropy of the universe o Entropy (disorder, randomness) is always increasing o In most energy transformations, living organisms convert organized forms of energy (chemical energy) to heat (which is less organized) o The quality of energy changes from organized to random Free energy —the portion of a system’s energy that can perform work when temperature is uniform throughout the system. “free” = available to do work Organisms live at the expense of free energy that they get from their surroundings ∆G = quantity of free energy of a system G = H – TS Where H = total energy of the system T = absolute temp (Kelvin; K = °C + 273) S = entropy Translation: not all the energy of a system is available to do work.
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