iMac ram Upgrade

I have a mid 2011 iMac and it only has 4gb of ram. I just upgraded my mid 2012 macbook pro and it only had 4 gb of ram that i had to take out to replace it with 8 gb of ram. My question is that can i put that 4gb of ram that i took out of my macbook and put it into the mid 2011 iMac because it has 4 slots of ram and is only using 2.

I am just making sure that if i do this that it won't screw up my computer and hurt it in any way because one ram is 1333 and the other is 1600