Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

تمرين 2

Activation Energy. As shown in Reaction 6-2, hydrogen peroxide, H 2 O 2 , decomposes to H 2 O and O 2. The activation energy, E A , for the uncatalyzed reaction at 20°C is 18 kcal/mol. The reaction can be catalyzed either by ferric ions ( E A = 13 kcal/mol)or by the enzyme catalase ( E A = 7 kcal/mol).
(a)Draw an activation energy diagram for this reaction under catalyzed and uncatalyzed conditions, and explain what it means for the activation energy to be lowered from 18 to 13 kcal/mol by ferric ions but from 18 to 7 kcal/mol by catalase.
(b)Suggest two properties of catalase that make it a more suitable intracellular catalyst than ferric ions.
(c)Suggest yet another way that the rate of hydrogen peroxide decomposition can be accelerated. Is this a suitable means of increasing reaction rates within cells Why or why not