Question

1. Enzymes lower activation energy which allows a reaction to occur at a faster rate. Why is it important, in terms of functionality, for enzymes to lower this activation energy? What happens when the physical environment in which the enzyme exists within is altered?

2.From a human perspective, cellular respiration is of an absolute importance in terms of how our bodies converts energy stored in glucose into ATP which our cells can use efficiently. What happens (to humans) when this process is not efficient and no longer functions within cells?

Answer 1

1. According to the collision theory of chemical reaction, the reacting molecules must collide with each other and must have sufficient energy to overcome the energy barrier for the reaction. At any given temperature, the molecules may not have sufficient kinetic energy to undergo a chemical reaction reaction and hence the frequency of collision between molecules will be very low. When activated energy is added to the system, there is an increase in the number of activated molecules and the reaction speeds up rapidly. Enzymes acts as catalyst which help in achieving the transition state or activated state at much lower energy by reducing the energy of activation and accelerating the rate of chemical reactions. So,by lowering the activation energy, enzymes bring the molecules in close proximity, reduce energy value for the reaction and speeds up the reaction.

The factors which affect enzyme activity are temperature, pH, enzyme concentrations, substrate concentrations, activators and inhibitors. There is an optimum temperature at which rate of reaction is maximum characterised by enzyme activity, but above the temperature , the reaction rate decreases due to thermal denaturation of the protein; followed by loss of secondary and tertiary structures. For pH, the optimal activity is between pH 5-9. Extreme pH changes lead to an alteration in the mode of binding of prosthetic groups leading to their dissociation. Hence, we observe that changes in the physical environment significantly affects the functionality of an enzyme rendering it to be non functional and even in some cases leading to their loss of structures.