Jessica,
Getting the combination of the degrees is up to you. When I was at UCLA working on drugs for the treatment of breast cancer, I was part of a very large team of researchers. I have a PhD in chemistry and was part of the "chemistry" team that synthesized a ligand that would later encapsulate a radioactive isotope for radioimmunotherapy and/or radio immunodetection. I handed off my molecules to a radio chemist that would insert the isotopes, and they in turn passed the compound on to a team of molecular biologists and biochemists that attached the compound to monoclonal antibodies that were derived from phages. Further down the chain were biologists, clinicians, and physicians who would test the samples in different vectors and assess effectiveness. Over the whole effort, and over the research grant, was an MD/PhD. His role was primarily administrative, but very important to holding this broad effort together.
It depends on the role that you want to play. There are jobs at every stage of the process, and all of them can be fulfilling.
