Turkish has no articles. If you wanted to substantiate it you would have to say something like; "Eat the bread" - "Bu ekmeği ye"...Using the accusative ending for the noun "ekmek" which you'll learn in a lesson or so!
In general. Turkish uses the accusative to substantiate. In the same way that you might find it in Swedish when you say "finger" for "finger", but "the finger" becomes "fingret". - There's a similar logic here.