DNA and God

In my biology lecture we started talking about cell reproduction. This means we start with DNA replication, and RNA translation and transcription; pretty much all the stuff that takes place when you get a new cell, proteins, etc. DNA is made up of a nitrogen base, a sugar (deoxyribose, or ribose), and a phosphate group. There are 4 nitrogen bases that make up DNA. They are adenine, cystosine, thymine, and guanine. Adenine attaches to thymine, and each cystosine attaches to a guanine making something like unto this:

...and so on.

The phosphates hold each sugar together, but the organization of everything made me ask my professor, "I understand that all these nitrogen bases have to match up, but why does it matter how everything else matches up vertically?" I had already run through the processes and came to the conclusion that everyone has to sort of have the same DNA, or that DNA had to have an origin, but I needed to hear my professor explain it. She said that DNA make up has to have been around for a long time. DNA make up, like above, doesn't just occur randomly since DNA is always replicated with an orginal piece. Sure there are adjustments that define how we look, but as far as each individual having 2 eyes, 10 toes, and a butt... that's been around forever.

My conclusion from all of this thinking, was that something so complex had to have a starting point. There had to be a point where the DNA for humans was introduced and man began. If it's so complex, why not?