Re: How does temperature affect the rate of the resipiration of Yeast?

Respiration, in yeast and all organisms, is a biochemical pathway which involves multiple enzymes.
Enzymes are proteins which catalyze chemical reactions.
Enzymes catalyze a reaction by decreasing the energetic barrier called the activation energy.

The activation energy is the energy required to impose on the reactants in order for them to be converted to products. It is the difference of the energy between the transition state and the reactants. The rate of enzymatic reactions are increased when the activation energy is lowered. The energy of a reactant(s) and transition state is determined by the equation:

DG= DH - TDS

(where H is enthalpy, T is Temperature, and S is entropy) When G is a negative value it is more energetically favorable. So, by this equation, when T is higher, the conversion of Reactant to Product is faster because it is more energetically favorable (lower activation energy) to change from the reactant to the transition state.

But, Enzymes are proteins. Proteins are made of amino acids bonded together in a polypeptide chain. Increasing the Temperature is indeed within limits because at much higher temperatures the bonds holding the protein will break and the enzyme will be destroyed.

At really low temperatures, alternatively, the reactions will be very slow, until enzymes and their substrates (the reactants) will not bind each other at a significant rate.