7. The active site model (also called the lock and key model) of enzyme -ubstrate binding differs from the induced fit model in which of the following ways? A. The induced fit model holds that the shape of the substrate is irrelevant to enzyme substrate binding B. The induced fit model holds that the shape of the active site is altered during the course of substrate binding C. The induced fit model holds that the shape of the active site is permanently altered by substrate binding D. The induced fit model holds that enzyme-substrate binding does not take place at the enzyme's active site 8. Which of the following enzyme types catalyzes the formation of a single bond between two substrates? A. Ligase B Oxidoreductase c . Isomerase D . Hydrolase 9. Enzymes undergo a decrease in catalytic efficiency in the presence of excess temperature but can regain this efficiency once temperature returns to normal: this suggests that increased temperature does not disrupt which of the following aspects of enzym structure? A. Peptide bonds B. Vander Waal's forces C . Hydrophobi c interactions D . Hydrogen bonds 10. Local conditions can affect the specificity of an enzyme for its substrate and thus the enzymes catalytic ability: which of the following alterations would most likely not affect an enzyme in this manner? A. Increased temperature B . Increased concentration of H+ C Increased substrate concentration D . Increased concentration of salts 11. Enzymes catalyze biochemical reactions by altering which of the following quantities associated with the reaction? A. The change in Gibb's free energy Delta G B. The equilibriun constant k_(eq) C. The enthalpy of formation Delta H D. The activation energy E_(a) 12 . Potassium cyanide is a poison which combines with cytochrome to prevent binding of oxygen to the enzyme without altering the Km of the reaction with respect to reduced cytochrome c . Which type of inhibitior does this represent? A Noncompetitive inhibition B . Reversible inhibition C . Competitive inhibition 13.In the first step of glycolysis hexokinase produces glucose-phosphate G-6-P itself can also bind to hexokinase at th e active site,blocking access to ATP. This is an example of: A . Allosteric inhibition B Feedback inhibition C Uncompetitive inhibition

Question

7. The active site model (also called the lock and key model) of enzyme -ubstrate binding differs from the induced fit model in which of the following ways? A. The induced fit model holds that the shape of the substrate is irrelevant to enzyme substrate binding B. The induced fit model holds that the shape of the active site is altered during the course of substrate binding C. The induced fit model holds that the shape of the active site is permanently altered by substrate binding D. The induced fit model holds that enzyme-substrate binding does not take place at the enzyme's active site 8. Which of the following enzyme types catalyzes the formation of a single bond between two substrates? A. Ligase B Oxidoreductase c . Isomerase D . Hydrolase 9. Enzymes undergo a decrease in catalytic efficiency in the presence of excess temperature but can regain this efficiency once temperature returns to normal: this suggests that increased temperature does not disrupt which of the following aspects of enzym structure? A. Peptide bonds B. Vander Waal's forces C . Hydrophobi c interactions D . Hydrogen bonds 10. Local conditions can affect the specificity of an enzyme for its substrate and thus the enzymes catalytic ability: which of the following alterations would most likely not affect an enzyme in this manner? A. Increased temperature B . Increased concentration of H+ C Increased substrate concentration D . Increased concentration of salts 11. Enzymes catalyze biochemical reactions by altering which of the following quantities associated with the reaction? A. The change in Gibb's free energy Delta G B. The equilibriun constant k_(eq) C. The enthalpy of formation Delta H D. The activation energy E_(a) 12 . Potassium cyanide is a poison which combines with cytochrome to prevent binding of oxygen to the enzyme without altering the Km of the reaction with respect to reduced cytochrome c . Which type of inhibitior does this represent? A Noncompetitive inhibition B . Reversible inhibition C . Competitive inhibition 13.In the first step of glycolysis hexokinase produces glucose-phosphate G-6-P itself can also bind to hexokinase at th e active site,blocking access to ATP. This is an example of: A . Allosteric inhibition B Feedback inhibition C Uncompetitive inhibition

Answer 1

7. The correct answer is B. The induced fit model holds that the shape of the active site is altered during the course of substrate binding. In the induced fit model, the enzyme's active site is flexible and can change shape to better fit the substrate, whereas in the lock and key model, the active site is rigid and the substrate must fit perfectly.8. The correct answer is A. Ligase. Ligase enzymes catalyze the formation of a single bond between two substrates, typically through the process of joining two molecules together with the concomitant hydrolysis of ATP.9. The correct answer is A. Peptide bonds. Enzymes are sensitive to temperature, and excess temperature can cause denaturation, disrupting the weak interactions that stabilize the enzyme's tertiary structure. However, peptide bonds, which link amino acids together in a protein, are much stronger and are not disrupted by temperature changes.10. The correct answer is C. Increased substrate concentration. Local conditions such as temperature and pH can affect an enzyme's activity, but increasing the substrate concentration does not affect the enzyme's specificity or catalytic ability.11. The correct answer is D. The activation energy

. Enzymes speed up chemical reactions by lowering the activation energy required for the reaction to occur, thereby increasing the rate at which the reaction reaches equilibrium.12. The correct answer is A. Noncompetitive inhibition. Potassium cyanide inhibits cytochrome c oxidase by binding to a site other than the active site, preventing oxygen from binding without altering the Km of the reaction with respect to reduced cytochrome C.13. The correct answer is B. Feedback inhibition. In this case, glucose-6-phosphate (G-6-P) binds to hexokinase at the active site, preventing ATP from binding and thus inhibiting the enzyme's activity. This is an example of feedback inhibition, where the end product of a metabolic pathway inhibits an enzyme involved in its own synthesis.

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