Meet the Chemist: Rosalind Franklin

Vocabulary flashcards covering the biographical details, scientific accomplishments, Photo 51 diffraction pattern measurements, and legacy of Rosalind Franklin.

Rosalind Elsie Franklin

A physical chemist (July 25, 1920 – April 16, 1958) born in Notting Hill, London, United Kingdom, who conducted X-ray diffraction work at King's College London and the University of Cambridge, best known for demonstrating the double-helix structure of DNA.

Photo 51

The famous X-ray fiber diffraction pattern image of B-form DNA, taken by student Raymond Gosling under Rosalind Franklin's leadership, which provided the key structural evidence for the DNA double helix.

Deoxyribonucleic acid (DNA)

The molecule containing the genetic instructions for the development of all living organisms, whose three-dimensional double-helix structure was revealed through Photo 51.

Raymond Gosling

The student working under Rosalind Franklin who took the actual Photo 51 X-ray diffraction image.

Rosalind Franklin Square

The official name given to Campus Square on the Leiden Bio Science Park in honor of chemist Rosalind Franklin.

Meridional arcs

The smears at the top and bottom of the Photo 51 fiber diffraction pattern originating from horizontal bases, used to calculate the interbase distance $h = 3.4\,\text{Å}$.

Helical pitch ($P$)

A measurement of the DNA structure determined by the spacing between layer lines in Photo 51, equal to $34\,\text{Å}$ with $10$ bases per turn.

Interbase distance ($h$)

The distance between consecutive horizontal bases in B-form DNA, measured as $3.4\,\text{Å}$ using the meridional arcs of Photo 51.

DNA Fiber Radius

The radius of the B-form DNA helix, indicated by the angle in the Photo 51 diffraction pattern as $10\,\text{Å}$.

1986 Criminal Case

The landmark year representing the first practical application of DNA evidence in a criminal case.