1. lon channel opening. Consider an ion channel that is initially open at $t = 0$, and opens and closes with probabilities per unit time $\alpha$ and $\beta$ respectively:
Let the probabilities of the ion channel being closed or open be $p_0$ and $p_1$ respectively.
a) List the parameters of this system. List the variables of this system.
b) Write down an ordinary differential equation, describing the rate of change of the open probability $p_1$. Express the right-hand side in terms of $p_1$ and the parameters of the system.
c) Solve the ordinary differential equation to obtain $p_1(t)$. Assume the channel is initially closed, such that the system satisfies the following initial conditions $p_1(0) = 0$.
d) At long times, i.e. when $t \to \infty$, write down an expression for the probability of the channel being open as a function of system parameters.
e) What is the time at which the system reaches half its steady-state value?