The answer is no, the system can't be charged over USB.  You need the original AC adapter that came with the system to charge the battery.  
Does anyone know if any of the the Inspirion 5379's allow charging by the USB port. I thought one of the two of them could be used when I purchased it.  However if it can I wanted to know if I needed a Special Cable to charge from a USB port into one of the two ports.  ThanksI'm off on Holiday on Monday and its a longer journey and wanted to keep it charged or running whilst on the Plane to watch a couple of movies. 
USB Port 5379