Question: What is a DNA double helix?

Michael Schneider answered on 11 Nov 2015:

Imagine a spiral staircase many stories high. The two strands of DNA are like the railings (or do you call them bannisters?), connected to each other by the steps. Each step is made up of two molecules that fit into each other like a key into a lock, and their are two kinds of pairs (“A” matches “T” and “C” matches “G”). When cells divide, the two strands separate entirely, and a new matching strand of DNA is made upon each. And, for cells to make the proteins they need for their structure and the things they do, small segments of DNA (genes) open up, and the specific order of As, Ts, Cs, and Gs is the “genetic code” that tells the cells which amino acid molecules to string together to make a protein (like having 24 kinds of beads in a necklace).