Dr. Holdren in the Institute's BioScience division would like you to retrieve a tissue sample from a specific Super Mutant. Once you've accepted this quest, head to the randomly selected location indicated on the Pip-Boy.
Considering the size of the Mutants in general and the likelihood that your designated location for this quest is indoors, you might as well take out all of the Mutants you encounter as you make your way to the Super Mutant targeted for this quest.
After killing the designated Super Mutant, pick up its tissue sample and return to Dr. Holdren to complete the quest.