There are two general places to view and update keyboard bindings in Ubuntu. The first is System / Preferences / Keyboard Shortcuts. If you are using Compiz, then there is another place to go to configure various visual effects and view/update keyboard bindings.

That is the CompizConfig Settings Manager and it is normally found at System / Preferences / Advanced Desktop Effects Settings. If you do not have that item available, then run the following command to install the necessary package:

$ sudo apt-get install compizconfig-settings-manager