Can you please post a picture of the implementation of such flip-flop at logic gate level? How can I easily change a positive edge triggered D Flip Flop to a negative edge? Also, how will the truth table differ from the positive edge?
here is link to datasheet for 74LS112 http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwj-wJ3vpt7ZAhVW9mMKHQDuCbwQFggpMAA&url=http%3A%2F%2Fwww.ti.com%2Flit%2Fpdf%2Fsdas199&usg=AOvVaw1bLUvWMKMq_A9rtgMzL0Bf
and here is logic-diagram
You should download a PDF of the TTL databook, and read it. Or buy a used copy, and flip through it.