I am going to concentrate on the underlying categorical issue here and leave the homological algebra to the experts in that subject. A **direct limit** is also known as a **colimit**. Yours, I take it, is over a sequence $N$, and as such is called **directed** or **filtered**. Being an short exact sequence $0\to A\to B\to C\to 0$ amounts three things: - $A\to B$ is a **monomorphism** or $0$ is its kernel, which are kinds of **limit** (or **projective limit** in old terminology), but **finitary** ones; - $B\to C$ is an **epimorphism**, or $C$ is its **image**, which are other kinds of **colimit* property, this time finitary ones. - the image of $A\to B$ is the kernel of $B\to C$, which combines properties of both kinds. Now, limits commute with limits and colimits commute with colimits. The question is whether **filtered colimits** commute with **finite limits**. At least, I presume that is what a **Grothendieck category** might mean.