I'm not sure what do you mean by "I'm half way through my master's program in biology" and "I will have my PhD a year from now" -- so are you finishing a MS or PhD student?
In any case, this quick story may motive you -- I know a professor from my alma mater was originally a physical chemist in practice. after the post-doc training, this prof switched to environmental chemistry for an academic position. And now, this professor is one of the leading environmental chemist in the field. so never say never, just think through and make a good plan, other things will fall into place.