ubuntu install on portable external hard drive through usb

I recently purchased seagate backup plus 1 tb portable external hard drive.
I am using windows 7.
So i want to install ubuntu on my external portable hard drive and use it as a seperate computer.
So whenever i take my portable external hard drive and connect it to other computer or laptop through usb.
i should be able to load linux and my files should be on that portable hard drive.

Is that possible if yes how should do it .

Basically i want my portable external hard drive as another mini laptop which should be able to work to whatever computer i connect.