How to draw a smooth curve in pgfplots? And how to remove y-axis ticks?

I'm preparing a presentation using Latex beamer. I've decided to include a plot.

The middle curve is supposed to be a normal distribution; but it has sharp corners. Why is that?

Also, can I remove the tick marks on the y-axis?

Here is my code:

\begin{frame}
\begin{tikzpicture}
\begin{axis}[domain=-1:1]
\addplot+[no markers] {4*exp(-4*(x+1))};
\addplot+[no markers] {1/sqrt(2*pi*0.02)*exp(-(x^2)/(2*0.02))};
\addplot+[no markers] {4*exp(4*(x-1))};
\end{axis}
\end{tikzpicture} 
\end{frame}

Thanks

• To get smooth curves, increase the number of sample points, e.g. samples=100

• To remove the y axis lables: yticklabels=\empty

\documentclass{beamer}

\usepackage{pgfplots}

\begin{document}

\begin{frame}
\begin{tikzpicture}
\begin{axis}[domain=-1:1,samples=100,yticklabels=\empty]
\addplot+[no markers] {4*exp(-4*(x+1))};
\addplot+[no markers] {1/sqrt(2*pi*0.02)*exp(-(x^2)/(2*0.02))};
\addplot+[no markers] {4*exp(4*(x-1))};
\end{axis}
\end{tikzpicture} 
\end{frame}

\end{document}