Unit of Work pattern and persistence

I have been reading about Unit of Work pattern but I am confused about how the UoW actually persists data.

When we commit the changes, UoW should iterate through the list of Added, Up开发者_如何学编程dated and Deleted objects and somehow find a class responsible to Add, Update, Delete objects of a certain type.

I couldn't find an example showing this technique.

Any advice on this would be greatly appreciated.

Mosh