Technoquest: The bald truth about fungi

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Q How do fungi differ from plants?

Fungi are quite like plants: they form complex, sometimes branching structures, they cannot move independently and they cannot respond to their environment as animals can.

The main difference lies in the way these two sorts of organism get their food. Plants can photosynthesise, using the light energy of the sun to fix carbon dioxide from the atmosphere, to form sugars. Fungi can't photosynthesise - they do not produce any chlorophyll. Instead, they secrete powerful enzymes to break down the material of living or dead organisms. This becomes their food, which they absorb through their cell walls rather than ingesting it as animals do. Fungi therefore have to grow in or on their potential food. Since they surround themselves with food-digesting enzymes, it is hardly surprising to find that their cell walls include a very tough protective material, chitin. (This material is also found in animal exoskeletons).

Q Why do men go bald?

It's because of a sex hormone, testosterone, which occurs naturally in all our bodies. All men produce about the same amount of testosterone - about 10 times as much as women - but some are more vulnerable to its effects than others. Testosterone causes baldness in the hair follicles that are sensitive to one of the hormone's breakdown products, DHT.

Every follicle tends to produce hair in phases - a growing phase followed by a shorter resting phase, after which the hair is shed, then a new one grows. DHT makes the follicles "rest" sooner and eventually shut down to become dormant. Treatments do exist - but you have to use them every day or the regrown hair just falls out again.

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