Connecting one of two Dropdown menu choices to list of things

Hey! Im a Bubble-newbie and I got a question:
I want to have two choices in a dropdown menu for instance - if the first choice is picked, e.g. ‘all universities’, a map should show all universities I entered in a list. If the second choice is clicked, e.g. ‘private universities’, the same map should show just the private universities I entered in another list.
The question is: How can I create those lists and link them to different choices of one and the same dropdown menu?

Thanks for help!!

Test the value of the dropdown selected, then update the data source of the map using the data list for the relevant selection using workflows.

Hey DaveA thanks for your quick help! I think I got an idea now, but could you tell me how to define the value of the dropdown selected?
That would be the last piece of my puzzle!