I am a mother of three two under the age of 4. I took intro to bio and intro to chemistry at the same time. They are very different classes so it worked well for me. Having the chemistry done definitely helped in both a & p and micro. I took nutrition as an online class over the summer in between anatomy 1 and 2. This worked well. I would recommend anatomy 1 and chemistry before micro. Microbiology has a very strong chemistry component and is a tough class. Also topics in micro like cell division and cellular respiration are introduced in anatomy 1.