can i safely use my macbook pro hdd (late 2011) on another macbook pro (late 2009)?

i have a gpu issue with my macbook pro late 2011 which requires 3 weeks in repair (until the required parts come in). I took out the hard-drive and put it in an external casing.

Can i safely use this hard-drive on another macbook pro (late 2009) and still use my data/applications/OS X?