This version (2016/04/28 01:09) was approved by svrijn.The Previously approved version (2014/09/08 22:46) is available.Diff

Diffraction pattern of DNA

Introduction

Obtaining the X-ray diffraction pattern of DNA can obviously not be done during a show. This experiment uses light diffraction to show what the diffraction pattern of DNA is. Then the obtained pattern can be compared to a real X-ray diffraction image.

Description of the Experiment

Small (< 1 mm) patterns of DNA are printed in black and white on a transparent sheet. Place a pattern in a laser beam and observe the diffraction pattern on a screen far from the sample. You should see a diffraction image similar to X-ray diffraction.

It is also possible to decompose the whole pattern of DNA into the several periodic pieces: length of one turn of the helix, separation betwee two bases, distance betwee the two strands… Each elementary pattern gives some of the peaks visible on the diffraction image of the whole DNA.

Safety Information

Usual safety issues with laser beam. A 1 mW red laser beam is enough in the dark.

Equipment and materials

  • Laser pointer (between 1 and 5 mW)
  • Transparent sheets on which patterns of DNA and other periodic patterns are printed. It should be possible to see the patterns by eye, or with a magnifying glass; otherwise it would not convince the audience)
  • White screen
experiments/diffraction_pattern_of_dna.txt · Last modified: 2016/04/28 01:08 by svrijn
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