Study Guide > University of Louisville BIO 240 Ch 8 Intro to Energy Notes

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University of Louisville BIO 240 Ch 8 Intro to Energy Notes Section 8.1  Metabolism- totality of an organism’s chemical reaction  A metabolic pathway starts when a molecule is changed in ... a series of defined steps, then, produces a specific product; each step is catalyzed by a specific enzyme  Metabolism manages the material and energy resources of the cell  Catabolism- the breaking down of complex molecules into simpler compounds (cellular respiration)  Anabolism- the building up of complex molecules (the synthesis of an Amino Acid)  Energy is the capability to cause change  Life depends on the ability of cells to transform energy from one form to another  Kinetic Energy- the relative motion of an object  Thermal Energy (Heat) - the kinetic energy that is associated with random movement of atoms or molecules.  Potential Energy- energy that matter possesses because of its location or structure (water behind a dam, above sea level)  Chemical Energy- the potential energy that is available for release in a chemical reaction  Thermodynamics- the study of the energy transformations that occur as a result in a collection of matter  Isolated system- unable to exchange either energy or matter with its surroundings  Open system- able to exchange energy and matter with its surroundings  1st Law of Thermodynamics (principal of conservation of energy) states that the energy of the universe is constant  2nd Law of Thermodynamics states that every energy transfer increases the entropy of the universe  Entropy is the measure of disorder, or randomness  A spontaneous process is one that can occur with no input of energy; this process is able to occur as a result of entropy  For a process to occur spontaneously, it must increase the entropy of the universe Section 8.2  (Gibbs) Free Energy- the portion of a system energy that can perform work when temperature and pressure are uniform through a system  ΔG = ΔH – TΔS  ΔH is the change in the systems enthalpy (total energy)  ΔS is the change in a systems entropy  T is the absolute temperature in Kelvins  If the ΔG is negative then the processes have the ability to be spontaneous  Systems with a high G (unstable) will change in a way that will make the system have a lower G (more stable)  Equilibrium is achieved when maximum stability is reached  When G is at its lowest possible value, in the system  Therefore, any change in G will be positive, and therefore not spontaneous  Exergonic reaction- a chemical reaction that proceeds with a net release of free energy: G will decrease  Endergonic reaction- absorbs free energy from its surroundings: G will increase Section 8.3  A cell does three kinds of work  Chemical work- the pushing of endergonic reactions that would not normally occur spontaneously  Transport work- the pumping of substances across a membrane against the direction of spontaneous movement  Mechanical work- the beating of cilia, contraction of muscle cells, and the movement of chromosomes  Energy coupling- use of an exergonic process to drive an endergonic one  ATP- creates the majority of the energy used in cells; made up of a ribose sugar, an adenine nitrogenous base, and three phosphate groups  Used in energy coupling and to make RNA, among other things  The bonds of the phosphate groups can be broken by hydrolysis  The breaking of this bond releases 7.2 kcal of energy per mole of ATP hydrolyzed  The breaking of the bond results in the ATP becoming ADP  The release of energy comes from the chemical change of state to lower free energy  The reason ATP is so useful is because it produces so much more energy than other molecules could deliver  When ATP is hydrolyzed, it typically releases heat; this is useful in some ways such as the heat released when shivering  It is important for cells to be able to transfer this heat into useful energy (chemical, transport, and mechanical)  With the help of ATP hydrolysis cells can couple endergonic reactions with the energy released from ATP to make them exergonic  This involves the transfer of a phosphate group from ATP to some other molecule (reactant)  This reactant with the bonded phosphate group is called the phosphorylated intermediate, which is the key to coupling reactions  Transport and mechanical work is almost always powered by ATP [Show More]

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