If it is a brand new subject, you may have to take preparation courses – because you’ll be competing with other grad students who do have this background. You don’t want to fail in grad school.

Be happy if they don’t require a complete undergrad major before grad school. They want to to succeed and you want to succeed – so they will probably steer you right. IF they say you need to take courses you feel you already know, ask if you can take a challenge test.

the worst thing is to NOT do it because they want you to take the extra courses. Don’t work in a career you are not that interested in just because of a couple of courses. You can probably take them on line, anyway.

good luck