Schools will initially only look at your GPA at the time of applying, but will likely require you to send them updated transcripts each semester. If your grades fall, they will notice and you may no longer be eligible.
Some programs require that certain (or all) prerequisites be finished or currently enrolled at the time of applying. Others only require that they are finished before the start date of the program. Those programs will want you to submit a written plan of when and how you will complete your remaining prereqs. If you are accepted but then don't finish a prereq in time you will be dropped. You'll need to check with each school to determine their policy. If this information isn't explicit on their website, call or e-mail an advisor.
Make every effort to complete pre-preqs as soon as possible. Schools are more likely to accept a student who has demonstrated their performance vs. an unknown. If all you are missing is dev-psych, that isn't too bad, but take it this summer or fall if you can. I've heard that schools are most interested in your A&P grades since A&P is closer to the difficulty level of grad school than most other pre-reqs.
Keep in mind that you have the option to take a year after graduation to work, volunteer, and finish any remaining pre-reqs. All these things will give your application a big boost.
