Yes, you can apply for OD at JNTUK without original memos. However, you will need the soft copies of your provisional certificate and original marks memo in a specific size. You will also need a scanned copy of your passport size photograph along with your scanned signature. 

There is another way to get your OD directly but it will cost you a little more than the online procedure. You can go to the university directly with the required documents and collect your OD.