10-The digestive system breaks down Sucrose (cane sugar) via the following react
ID: 200418 • Letter: 1
Question
10-The digestive system breaks down Sucrose (cane sugar) via the following reaction: Sucrose + H2O Glucose + Fructose AG 63kcalinol). However, in pure aqueous solution, Sucrose can last for months without undergoing any noticeable hydrolysis. a. Explain why such a thermodynamically favorable reaction would not readily take place. b. Which factor produced by the digestive system allows this reaction to actually take place? c. Which parameter of the reaction does this factor specifically change? d. How does this factor affect the way the reaction reaches equilibrium? e. Will this factor affect the free energy change of the reaction? 11-Consider the following reaction X Y and the energy diagram represented on Figure 1. a- For each reaction path, write the expression of the activation energy and the total energy change of the reaction (use the energy levels indicated by a, bc and d). b- Which of the two paths suggests the presence of a c catalyst (like an enzyme)? c- Which class will that enzyme belong to if i- X is a phospho-protein and Y is the non- phosphorylated form of X. i- Y is the phosphorylated version of protein X. ili-X is Maltose and Y is Glucose. iv-X is Glucose 1-phosphate and Y is Galactose-1-phosphate. V- X is ethanol and Y is acetaldehyde. vi-If X is pyruvate and Y is acetaldehyde. Figure 1 Reaction pathway 12- What are the different mechanisms involved in substrate activation by the active site? 13- What is the difference between substrate specificity and group specificity 14- Hexokinase catalyses the first reaction of glycolytic pathway by phosphorylating Glucose as follows Glucose + ATP Glu cose-6-phosphate + ADP Figures 2A and 2B show the result of the kinetics study of the reaction at varying concentrations of Glucose and a fixed and saturating concentration of ATP a- Use figure 2A to estimate Vmas and Kw; what is the meaning of each of these parameters? b- Use figure 2B to determine Vmax and KM in the absence of inhibitor. c- What is the effect of each inhibitor 1 and 2 on the reaction? Discuss the type of each inhibitor and determine the corresponding KM and Vmax values. d- The same enzyme can also phosphorylates fructose with a KM of 1.5mM; which of glucose and fructose does the enzyme have a higher affinity for?Explanation / Answer
Answer:
10. (a) The reaction would not readily take place because the activation energy is much larger than the average kinetic energy of the molecules.
(b) The enzyme sucrase hydrolyses sucrose into glucose and fructose. Sucrase reduces the activation energy of the reaction so that the kinetic energy of most molecules exceeds the activation energy required and so they can react.
(c) Sucrase lowers the activation energy of the reaction such that it can take place.
(d) Sucrase lowers the activation energy. Since the activation energy becomes much smaller than the average kinetic energy of the molecules, the fraction of molecules possessing the necessary kinetic energy will be large; most collisions between molecules will result in reaction, and the reaction will occur rapidly.
Thus, sucrose turns into glucose and fructose (i.e. the equilibrium lies in the direction of the product).
(e) Sucrase decreases the Gibbs free energy of activation, but it has no effect on the free energy of reaction.
(Since there are multiple questions, the first full question have been answered according to the rules of Chegg)
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