Image Caption
DNA crystals look the same when turned upside down and backwards.
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This image is part of a series:
![Heredity tree as a puzzle piece.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/35299_evo_resources_resource_image_135_original.gif)
Puzzle piece (1 of 10) – heredity
DNA is the component of chromosomes that carries genetic information.![DNA helix as a completed puzzle.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/67858_evo_resources_resource_image_144_original-350x279.gif)
Puzzle piece (10 of 10) – Evidence for the structure of DNA
Watson and Crick figured out how all the evidence fit together but the evidence came from many different members of the scientific community.![DNA bases as puzzle pieces.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/69785_evo_resources_resource_image_136_original-350x350.gif)
Puzzle piece (2 of 10) – DNA structure
DNA is composed of phosphates and sugars attached to nitrogenous bases, which are arranged in stacks and always have the same ratio.![DNA as a puzzle piece.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/9410_evo_resources_resource_image_137_original-350x350.gif)
Puzzle piece (3 of 10) – DNA structure
DNA has a regular structure arranged in a helix.![Water molecules as a puzzle piece.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/8033_evo_resources_resource_image_138_original-350x117.gif)
Puzzle piece (4 of 10) – DNA structure
Franklin and Gosling find that water molecules can cling to the DNA.![Phosphate placement on the DNA model as a puzzle piece. Below, the puzzle is slowing being put together.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/36003_evo_resources_resource_image_139_original-350x350.gif)
Puzzle piece (5 of 10) – DNA structure
Based on the ease with which DNA took up water, Franklin reasoned that the phosphates (which attract water) must be on the outside of the helix.![Puzzle piece of atomic orientation arrows](https://undsci.berkeley.edu/wp-content/uploads/2022/08/11416_evo_resources_resource_image_140_original-350x126.gif)
Puzzle piece (6 of 10) – DNA symmetry
DNA crystals look the same when turned upside down and backwards.![](https://undsci.berkeley.edu/wp-content/uploads/2022/08/36088_evo_resources_resource_image_141_original-350x350.gif)
Puzzle piece (7 of 10) – DNA helix
Image B 51 also suggested the number of bases per twist and the diameter of the helix.![Two puzzle pieces being added to a more and more complete puzzle of DNA.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/85490_evo_resources_resource_image_142_original-350x248.gif)
Puzzle piece (8 of 10) – DNA structure
The DNA puzzle after the addition of the stacked bases and helix diameter findings.![Flat atomic model of DNA bases as a puzzle piece.](https://undsci.berkeley.edu/wp-content/uploads/2022/08/9001_evo_resources_resource_image_143_original-350x126.gif)