DNA: The spiral in the helix

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DNA, our genetic material is a macromolecule that is long and linear that rolls up to have a spiral-like configuration. We refer to the spiral shape of DNA as a helix. In nature the DNA spiral comprises two strands arranged parallel to one another. The two strands are joined with hydrogen bonds. Taking this into account, we refer to a DNA molecule as a double helix. So, let’s consider the configuration of a DNA molecule without looking at the detail of the chemical components of DNA.

 For scholars: A demonstration of DNA’s helix configuration

A. Take a sheet of A4 paper and mark a 1 cm strip along the long edge. Draw inside the 1 cm strip a ladder that represents a DNA molecule.

B. Cut the 1 cm strip off the A4 paper.

C. Take the strip of paper and role it around a pencil.

D. Gently pull the pencil out. The spiral of paper represents the shape of a DNA molecule.