How does expected utility theory treat losses?
Gains and losses presuppose a reference point, which is not a feature in standard expected utility theory. In this theory, the only argument in the utility over wealth is $w$, the absolute level of wealth. A common form of utility function is the constant relative risk aversion (CRRA) form: 
\begin{equation}
u(w)=\frac{w^{1-\rho}}{1-\rho},
\end{equation}
where $\rho$ is the coefficient of relative risk aversion. Note that this incorporates the commonly seen $\sqrt w$ and $\ln w$ forms when $\rho$ is $\frac12$ and $1$, respectively. As is obvious, there is no term that helps differentiate between gains and losses in this formulation. The graph for a standard EU function with risk aversion is the same as any strictly increasing and strictly concave function. 

Prospect theory is motivated by empirical regularities found in psychology experiments. A typical utility form is 
\begin{equation}
u(x,r)=
\begin{cases}
(x-r)^\alpha &amp;\text{if }x\ge r\\
-\lambda(r-x)^\beta &amp;\text{if }x&lt;r
\end{cases}
\end{equation}
where $x$ is the payoff from some choice alternative (or "prospect" if the choice involves risks), $r$ is the reference point (which is $0$ in your example), $\alpha,\beta\in(0,1)$ are parameters that govern the degree of risk preference, and $\lambda$ is a parameter that separately captures loss aversion. Tversky and Kahneman (1992) estimate that $\alpha=\beta=0.88$ and $\lambda=2.25$.