Basics > Modeling Kinetics
> Mass Action >Exercises
Mass action rate laws:
Mass action kinetics state that the
rate of a reaction is the product of a rate constant (k) times (*) the
mass(S). The mass in our case is concentration of the substrate (S) of
the reaction. kS
Mass action kinetics can be used
to model (approximate) the behavior of reversible and irreversible enzymatic
reactions for unregulated enzymes that are not near saturation.
Modeling reversible and irreversible
reactions with mass action kinetics.
irreversible reactions (uni-directional)
- Irreversible reactions are
reactions that occur in only one direction. This includes uni-directional
movement across a membrane through a channel and enzyme catalyzed reactions.
For reactions with a single substrate, the rate law for the reaction is
written k*S or simply kS.
writing rate equations
- The phrase "reversible
reaction" is often applied to at least two types of biological events.
One event includes the reactions mediated by a single enzyme. This enzyme
catalyzes the transition or transformation of molecules between two states.
The second event is that the transition between the two states is mediated
by two different enzymes. This latter event is the result of two opposing
Stella example and exercise: