. Gene expression levels can be measured with a technique called qPCR. The results are analyzed using the "delta delta Ct" method which gives a fold change in expression level on a logarithmic scale with base 2. Let y be the expression level, then AACt = -log2(y). Suppose a plot of AACt is fit with a regression line AACt=-25t as shown below. -2 (a) What is the AACt at time t = 0? time t = 2? time t = 4? time t = 8? What is the expression level at these times? (b) Combine the equation defining AACt with the equation for AACt as a function of time into a single equation. This equation relates the expression level, y, with the time, t. Your answer should be written as a base 2 logarithm. (c) Rewrite this equation in exponential form. Your answer should be written as a base 2 exponential. (d) Find the doubling time for the expression level, y. (e) During one doubling time for y, how does y change? During one doubling time for y, how does AACt change? Write one sentence for each question.