The only thing DNA really does is code for proteins. Everything in our bodies is a result of the action or existence of proteins. Proteins form structures, comprise messengers and messages, start reactions and stop them--everything. There is no magic effluvium that tells your eyes to be blue--it's a protein. And no ethereal spirit tells your cochlea to signal your temporal lobe that the bells are ringing--it's protein. Some people think that describing life this way is "dehumanizing". Have you ever examined the simplest of protein reactions? They are amazingly complex yet exquisitely precise--far beyond one of our paltry pieces of machinery in their power and consistency. We are fearfully and wonderfully made!
...the plasma membrane! Diffusion, osmosis, polarization, depolarization, secretion, excretion, respiration...everything that means life. Without its exquisite and specialized "semi-permeability" we would never have developed beyond a single cell. But even so, single celled organisms--bacteria, viruses, protists--are the most successful life forms ever, with just one membrane! Many poisons work by "fooling" the plasma membrane--using an existing membrane function to invade and damage the cell's metabolic processes. So--always know exactly what's in the substances you ingest. Just because something is "natural" DOES NOT mean it is healthy! Arsenic, radon, cyanide, carbon monoxide--all are " natural" substances that cross the plasma membrane and destroy the cell. And guess what? Destroyed cells-->destroyed organism! So--be kind to your membranes today!