* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Pre-Test
Survey
Document related concepts
Light-dependent reactions wikipedia , lookup
Biochemical cascade wikipedia , lookup
Photosynthesis wikipedia , lookup
Citric acid cycle wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Metabolic network modelling wikipedia , lookup
Biochemistry wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Enzyme inhibitor wikipedia , lookup
Biosynthesis wikipedia , lookup
Transcript
1 . The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of: a catabolic pathway 6 . an energy-releasing pathway The free energy of the enzyme is greater than the free energy of the substrate, which attracts the substrate to the enzyme. a pathway in which the entropy of the system increases A positive charge on the substrate is attracted to a negative charge in the active site of the enzyme. The first and second choices are correct. The enzyme has the ability to change its configuration in response to the substrate binding. The first, second, and third choices are correct. 2 . Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is incorrect? This reaction is spontaneous with the release of free energy. A hydrophobic group on the substrate interacts with several hydrophobic amino acids on the enzyme. 7 . Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken. The free energy lost in this combustion is greater than the energy that appears as heat. The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction. The binding of two substrates in the active site provides the correct orientation for them to react to form a product. The reverse reaction, making glucose from water and carbon dioxide, must be an endergonic reaction. All of the above are ways that enzymes can speed up the rate of a chemical reaction. Which of the following statements about equilibrium of chemical reactions is correct? (Concept 8.3 ) [Hint] Reactions can only go in the direction toward equilibrium. 8 . Most reactions in a living cell are close to equilibrium. A reaction that is at equilibrium is not capable of doing any work. The compound causes a cofactor to be lost from the enzyme. None of the statements above correctly describes some aspect of equilibrium. The first and second choices are correct. Which of the following statements about ATP (adenosine triphosphate) is incorrect? (Concept 8.3 ) [Hint] The hydrolysis of ATP is an endergonic process that can supply needed energy for anabolic pathways. The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. Much of the free energy released on the hydrolysis of ATP is available to do cellular work. In many cases, ATP makes energy available to other reactions by transferring its phosphate group to the substrate for another energy-requiring reaction. 5 . The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Which of the following could account for this observation? (Concept 8.4 ) [Hint] The compound is a competitive inhibitor. The compound is a negative allosteric regulator. The equilibrium point of a reaction represents the least stable configuration for that reaction. 4 . Which of the following is not a way in which an enzyme can speed up the reaction that it catalyzes? The active site can provide heat from the environment that raises the energy content of the substrate. The entropy of the products is greater than the entropy of the reactants. The entropy of the universe increases as the result of this reaction. 3 . Which of the following would be unlikely to contribute to the substrate specificity of an enzyme? (Concept 8.4 ) [Hint] A similar shape exists between a pocket on the surface of the enzyme and a functional group on the substrate. Enzymes are described as catalysts, which means that they are proteins provide activation energy for the reactions they facilitate increase the rate of a reaction without being consumed by the reaction can alter the free energy change (ΔG) for a chemical reaction increase the free energy of the reactants in order to make the reaction go faster The first three choices are correct. 9 . Which of the following statements about feedback regulation of a metabolic pathway is incorrect? (Concept 8.5 ) [Hint] The final product of a metabolic pathway is the compound that regulates the pathway. The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate. The enzyme that is regulated by feedback inhibition is usually the first enzyme in the metabolic pathway. The compound that regulates the pathway acts as a noncompetitive inhibitor or a negative allosteric regulator. Accumulation of the product of the pathway will tend to slow down further formation of that product. Catabolism vs. Anabolism Examples? Laws of Thermodynamics 1. Conserve E a. Potential b. kinetic 2. Increase Entropy Energy Flow in Rxns High to low or require E input Free energy (delta G) Exergonic Endergonic Depends on Concentration of reactants Coupled Rxns ATP Enzymes Catalyst What does this mean? What changes? Transition state Intermediate Energy of Activation Regulate Rxn How? Inhibitors and Activators Competitive inhibition Noncompetitive inhibition Cooperative allosteric activation and inhibition Feedback Inhibition Redox Reaction