There is no link...they make you take the prerequisites mainly to ensure you can handle a massive workload...although the biology does help.
Heres a quick curriculum breakdown:
Genes-cells (basic bio)
All sections include anatomy, physiology, biochemistry, and basic imaging (xray/CT/ultrasound/MRI)
In addition, a course is given on talking to patients and taking vitals.
All sections include pathology, pathophysiology, microbiology, and diagnosis.
In addition, you take a class which goes over physical exams of each body part and continue refining patient interaction.
Rotate through the following areas of medicine in the hospital:
Medicine (10 weeks)
Surgery (8 weeks)
OB/GYN (6 weeks)
Pediatrics (6 weeks)
Psychiatry (6 weeks)
Family Practice (6 weeks)
Neurology (4 weeks)
Primary Care Outpatient (6 weeks)
Anesthesiology (2 weeks)
Emergency Medicine (2 weeks)
Geriatric and Palliative Care (6 weeks)
Take 20 weeks worth of electives and finish the above rotations.
Go on residency interviews and match to the specialty you want
This is just how it is at my school. Other schools do it differently.