AP Biology Chapter 8 (Refer to Reading Guide) – Flashcards
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According to the induced fit hypothesis of catalysis...
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The binding of the substrate changes the shape of the enzyme's active site.
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A no competitive inhibitor...
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Changes the shape of an enzyme's active site.
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Catabolism
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Cellular process of breaking down large molecules into smaller ones.
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Anabolism
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Consume energy to build up polymers from monomers.
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Metabolism
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Totality of an organism's chemical reactions.
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For living organisms, what is an important consequence of the first law of thermodynamics?
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The organism must obtain all the necessary energy for life from its environment.
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Why is ATP an important molecule in metabolism?
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It provides energy coupling between exergonic and endergonic reactions.
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Allosteric enzyme regulation is usually associated with...
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An enzyme with more than one subunit.
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Contrast the catabolic and anabolic pathways.
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Catabolic- releases energy by breaking down. Anabolic- consumes energy by synthesis.
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Energy
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Capacity to cause change.
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Kinetic Energy
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Energy of motion.
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Heat/Thermal Energy
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Kinetic energy associated with random movement of atoms or molecules.
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Chemical Energy
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Potential energy available for release in a chemical reaction.
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Thermodynamics
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Study of energy transformations that occur in a collection of matter.
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1st Law of Thermodynamics
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The energy of the universe is constant.
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2nd Law of Thermodynamics
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Every energy transfer increases the entropy of the universe.
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Free Energy
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Portion of a system's energy that can perform work.
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Contrast exergonic and endergonic reactions.
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Exergonic- release energy. Endergonic- energy required, absorbs free energy.
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How do you know if a reaction is spontaneous?
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The free energy of the system decreases; the system becomes more stable, released free energy can be harnessed to do work.
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Can a closed system at equilibrium do work?
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No, not without the energy from ATP.
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List and give an example of the three main kinds of cellular work done by ATP.
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1. Chemical- polymers to monomers. 2. Transport- pumping substances across a membrane. 3. Mechanical- contraction of muscles.
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Phosphorylated
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Addition of a phosphate group to a molecule.
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Explain the concept of coupled reactions and ATP doing work.
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One reaction makes ATP from ADP and the the next reaction breaks ATP down for energy. Without energy, ATP can't work.
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What is the relationship between exergonic reactions, endergonic reactions, and the use and regeneration of ATP?
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An exergonic reaction is energetically favorable. It will occur spontaneously and doesn't require energy. An endergonic reaction requires added energy and will not occur spontaneously. In nature, cells use ATP as an energy transporter. Energy is stored in ATP with the addition of a 3rd phosphate group to ADP, and energy is released when ATP is hydrolyzed to ADP. This energy is used to drive unfavorable reactions.
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Activation Energy
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The minimum quantity of energy that the reacting species must possess in order to undergo a specified reaction.
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Substrate
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Reactant an enzyme acts on.
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Enzyme Substrate Complex
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Enzyme binds to substrate.
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Active Site
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Part of enzyme that attaches to substrate.
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Induced Fit
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Change in shape of active site that enables substrate to better fit with enzyme.
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How does temperature and pH affect enzyme activity?
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Increase in temperature increases enzyme activity, enzymes have optimal temperatures at which they work, too high of a temperature denatures the enzyme. Enzymes work at optimal pH's, too low or high denatures the enzyme by changing its active site.
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Compare and contrast competitive and noncompetitive inhibitors.
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Competitive- reduce enzyme reactions by blocking substrates from enter active sites. Noncompetitive- reduce enzyme reactions by binding to a site away from active site, changes the active site so substrates can't attach.
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What is allosteric regulation and how does it assist in the regulation of metabolism?
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Protein function at one site is affected by the binding of regulatory molecule to a separate site. ~inhibitor binding stabilizes the inactive form of the enzyme. ~activator binding to a regulatory site stabilizes the shape that has functional active sites.
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Cooperativity
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~One substrate molecule primes an enzyme to accept additional substrate molecules. ~Works with enzymes that have 2 or more subunits.
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How does feedback inhibition work?
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Metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.
