(SPOILERS) When Lockdown tears out the Spark out of Ratchet, I noticed that he doesn't destroy it, it's like he collects these. Many questions came to mind when I saw him doing this, unlike other scenes where the Spark is completely destroyed, Lockdown keeps it inside some type of tube. Lockdown probably is asked to collect Sparks for the Architects/Creators to to build new life. Another possibility is that Lockdown gets rich selling these Sparks to the higest bidder, but that sounds a bit too silly let's leave that to the animated series. I like to think that Lockdown has been collecting Sparks for ages and maybe the last piece to his mission was Optimus, but alive. If you care to elaborate on your own theories please do, as the new film left out some very interesting things out.