Microbiology: How Bacteria Swap Genes Without Sex
The invisible world that shapes human health, from bacteria, viruses, fungi and parasites to the ways we kill them and the ways they fight back.
Try 3 questions
1. What does a Gram stain actually reveal about a bacterium?
- Exactly which drug will cure it
- How its cell wall is built
- Whether it is alive or dead
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Answer: How its cell wall is built
Bacteria with a thick peptidoglycan wall hold the purple dye (Gram-positive), while those with a thin wall and outer membrane lose it and stain pink (Gram-negative).
2. The old claim that bacteria in your body outnumber your own cells ten to one has been revised. What is the current estimate?
- About a hundred bacteria per cell
- About one bacterium per hundred cells
- Roughly equal numbers of each
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Answer: Roughly equal numbers of each
Recalculations suggest around 38 trillion bacteria versus about 30 trillion human cells, most of the bacteria living in the colon.
3. Why can some bacteria, such as Clostridium, survive boiling water for hours?
- They form tough, dormant endospores
- Their proteins never unfold in high heat
- They repair heat damage faster than it occurs
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Answer: They form tough, dormant endospores
Endospores are dehydrated, multi-layered resting forms that withstand heat, drying and chemicals; that is why sterilization needs pressurized steam.
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