Auxins: messengers of light

Auxin in the snow

Charles Darwin performed experiments on plant movements with his seventh child, Francis Darwin, which they wrote up as joint authors in 1880 (Francis was a young man at the time). Every year, thousands of children and budding scientists repeat these experiments:

  1. Shine a light on a plant from just one source, and observe as plants orientate their growth to ‘face’ the light.
  2. Adorn growing shoots with a ‘cap’ that is impermeable to light and observe as they grow straight, even as light hits the open stem.

The tip of the plant senses the direction of the light, and this information is transmitted to the growing stem to direct growth behaviour. That transmission is performed by auxins, the first of which was isolated in the 1930s.

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Carvone: through the looking glass

No one could mistake the pungent, spicy smell of caraway on rye bread, or perhaps in a yoghurt pudding, for the sharp, fresh smell of spearmint pinched from the garden or flavouring your tea. The two are entirely distinct. And yet the chemicals that make these two smells are identical in every possible way, except that they are mirror images of each other (‘enantiomers’).

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Caffeine: protector of plants

Caffeine molecule in the snow

Ah, the smell of coffee brewing, of tea steaming, hot chocolate beckoning on a cold winter’s day… the fizzy kick of Coca-Cola on a long journey. It’s wonderful, really. The taste, feel and cultural significance of each of these drinks may differ, but they all share one key ingredient: caffeine. Caffeine is the most commonly used mood-altering drug for humans: it wakes us up, prepares our minds for work, keeps us alert (we think) and provides a shared experience during informal interactions.

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Aspirin: the first modern drug

Aspirin in the snow

Preparations derived from willow have been a regular feature of the human medicine cabinet for centuries: Ancient Egyptians drank willow ‘tea’ to relieve pain, and the Classic Greek physician Hippocrates wrote about the remedy in 400 BC. But it took a team of German chemists in 1897, working for Bayer, to synthesise a pure compound related to the active substances in willow, acetylsalicylic acid. They packaged it up neatly in pill form, and sold it under its trademarked name, Aspirin, which quickly became a household word.

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