\begin{frame}
\small

\vspace{-1ex}

\begin{block}{}
A team of genetic engineers decides to create cows that
produce cola instead of milk. To that end they have to
transform the DNA of the milk gene
\[
\mG{TAGCTAGCTAGCT}
\]
\vspace{-3ex}

in every fertilized egg into the cola gene
\[
\mG{CTGACTGACT}
\makebox[0mm][l]{\hspace{15mm}
\smash{\raisebox{1ex}{\includegraphics[height=12ex]{../graphics/cow.png}}}}
\]
\vspace{-3ex}

\onslide<2->
\noindent
Techniques exist to perform the following DNA substitutions
\begin{gather*}
\mG{TCAT} \fromto \mG{T}
\quad
\mG{GAG} \fromto \mG{AG}
\quad
\mG{CTC} \fromto \mG{TC}
\quad
\mG{AGTA} \fromto \mG{A}
\quad
\mG{TAT} \fromto \mG{CT}
\end{gather*}
\onslide<3->
Recently it has been discovered that the mad cow disease is
caused by a retrovirus with the following DNA sequence
\[
\mG{CTGCTACTGACT}
\]
\vspace{-3ex}

\noindent
What now, if accidentally cows with this virus are created?
According to the engineers there is little risk because this
never happened in their experiments, but various action groups
demand absolute assurances.
\end{block}

\end{frame}