= Solution
Write the parameters as \b[$\pi_0,\pi_1,\mu_0,\mu_1,\sigma_0,\sigma_1$], where $\pi_j$ is the fraction of molecules in component $j$, $\mu_j$ is its <mean> current, and $\sigma_j>0$ is its current <standard deviation>. The <mixture weights> satisfy $\pi_j\geq0$ and $\pi_0+\pi_1=1$. Thus six displayed parameters represent \b[five independent degrees of freedom].
Assigning component 1 to modified molecules makes $\pi_1$ the inferred modification fraction. That biological assignment needs a reference or other identifying information: exchanging both component labels leaves the <Gaussian mixture distribution> unchanged. In the illustrated multi-sample model, component locations can be shared while the sample-specific fractions differ; this is different from fitting unrelated <means> to every sample.
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