Unusable energy entropy c chemical equilibrium i rate

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Unusable energy = entropy c. Chemical equilibrium i. Rate of formation of products equals the rate of formation of reactants 24) Distinguish between exergonic and endergonic reactions in terms of the energy of the reactants and products and the free energy change a. Exergonic: i. Spontaneous ii. Negative G b. Endergonic i. Positive G ii. Requires energy // not spontaneous 25) Describe how cells use the energy released by the hydrolysis of ATP to drive endergonic reactions a. Coupling exergonic reactions with endergonic reactions b. Phosphorylation i. In a coupled reaction a phosphate is directly transferred from ATP to glucose 1. Coupled reaction proceeds spontaneously because the G is negative 26) Explain how enzymes increase the rates of chemical reactions by lowering the activation energy a. Catalysts speed up reactions b. Chemical reactions between bond breaking and bond forming i. When a covalent bond is broken or formed 1. Involves the straining or stretching of one or more bonds a. Transition state i. Bonds have stretched to their limit ii. Enzymes lower activation energy so that small amount of heat can push reactants into the transition state
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27) Describe how enzymes bind their substrates with high specificity and undergo induced fit a. Active site: location in an enzyme where reaction takes place b. Substrates: reactant molecules that bind to an enzyme @ the active site c. Enzyme-substrate complex: binding between enzyme and substrate Induced fit: conformational changes that cause a substrate to bind more tightly to the enzyme 28) Explain how additional factors, such as non protein molecules or ions, temperature, and pH, influence enzyme activity a. Vmax: velocity of chemical reactions near its maximal state b. Km: substrate concentration at which the velocity is half its maximal value i. High Km: requires a higher substrate concentration ii. Low Km: bind to substrates more strongly c. Reversible inhibitors i. Competitive inhibitor 1. Molecules that bond to active site and inhibit the ability of the substrate to bind 2. “Fake” molecule ii. Noncompetitive inhibitor 1. Lowers the Vmax for a reaction without affecting the Km 2. Binds to an enzyme outside the active site a. Called an allosteric site d. Irreversible inhibitors i. Bind covalently to an enzyme to inhibit its function ii. Permanently inactivate an enzyme = less efficient e. Other factors that influence enzyme function: i. Prosthetic groups 1. Small molecules permanently attached to enzyme and aid in function ii. Cofactors 1. Inorganic ions that bind to enzyme and promote a chemical reaction iii. Coenzymes 1. Organic molecules that temporarily bind to an enzyme and participate in the chemical reaction that the enzyme catalyzes a. Left unchanged when the reaction is completed iv. Environment 1. Temperature (humans: 98.6 o F), pH, and ionic conditions 29) Explain the concept of a metabolic pathway and distinguish between catabolic and anabolic reactions a. Metabolic pathway i. Chemical reactions coordinated with each other
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in a series of steps b.
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  • Fall '19
  • Enzyme, Adenosine triphosphate

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