Did you have even a basic course in chemistry, molecular biology or organic chemistry, and physics?
If so, you would understand that the essential governing forces, bond formation, secondary and tertiary structure of compounds naturally resulted in the shape and structure of DNA.
The essential governing forces are described by equations that include measured dimensionless constants that cannot deviate appreciably before the current universe becomes uninhabitable. Somehow, these constants appear to have been selected for fitness.
"...The strong nuclear force coupling constant holds together the particles in the nucleus of an atom. If the strong nuclear force were slightly weaker, multi-proton nuclei would not hold together. Hydrogen would be the only element in the universe.
If this force were slightly stronger, not only would hydrogen be rare in the universe, but the supply of the various life-essential elements heavier than iron (elements resulting from the fission of very heavy elements) would be insufficient. Either way, life would be impossible..."
Other examples of this type can be found here:
http://www.reasons.org/resources/apologetics/design.shtml?main