I was somewhat clueless as to what I wanted to do during my first two years in university, but have recently (after my third year) begun to really enjoy molecular biology. I have decided that I want to do graduate studies (leading to a PhD) in molecular biology or a related field. I'm currently in my fourth year and have no actual research experience, though my grades are decent. Knowing that I can only gain a small amount of research experience in my final year, would it be a good idea to do a either a double major in biology and molecular biology and biochemistry (MBB) or possibly a minor in health science with a major in MBB instead of just graduating with a major in MBB? Both the double major and the major with a minor would require the same amount of time (~32 credits each). The extra courses in both cases, for the most part, would be related to molecular biology. With the extra year, I would have ample time to gain research experience, volunteer in a lab, increase my GPA and do an honors thesis.
I realize that there are many other aspects to an application, but based solely on increasing my GPA and gaining research experience, is it worthwhile to do an extra year of study before applying to graduate programs?
Any advice is appreciated.