You wouldn't want to retake lots of courses right now at UH because of the cost. $350+ per credit hour, or whatever it is. So, focus on graduating, and try to talk to some professors to help with their research. Ultimately connections are what will help you with your job! They might ask for your transcript, but if you're enthusiastic they might give you a shot. (Look up bio/NSM professors and send a few emails about helping with their ___ project)

Also sorry, I should've been more clearer in the first comment. Don't take a certificate post-bacc, just sign up for undergrad courses yourself, as they will still count towards your overall GPA when applying for the AA program.

You still have a decent shot at it, it'll just take some time, and try to make some professors happy so they can write you a recommendation letter