Category: Maths

Modular origami

270 (sonobe colourchange) [CC-BY-SA-3.0 Steve Cook]

A few months ago, I went to a creative origami lunchtime session organised by some lovely people at $WORK. I’d done origami a bit when I was younger, but mostly just frogs and cranes, which have since helped me while away the hours when invigilating exams. However, at this lunchtime session I was shown how …

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Organism of the week #28 – Fractal art

Barnsley fern [Public domain]

Flowers are essentially tarts. Prostitutes for the bees. (Uncle Monty, Withnail and I) Our tiny garden has only passing acquaintance with sunshine, so about the only plants that really thrive in its dingy clutches are shade-loving ferns. This Japanese painted fern is my current favourite: who needs flowers anyway, when leaves look like this? The colour is spectacular, but …

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Living dangerously

Towards the end of the last millennium, I spent a lot of time befriending arsenic. The last two years of my PhD involved measuring how much iodine had fallen off a chemical used as a wood preservative day-in, day-out, and arsenic trioxide was the most exciting component of an otherwise excruciatingly dull test for iodide ions. …

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Organism of the week #16 – From tiny acorns do mighty oaks grow

Sequoia sempervirens strobili and seeds [CC-BY-SA-3.0 Steve Cook]

There’s something very satisfying about growing plants from seed, and none more so than growing a monster from next-to-nothing: At the moment, this little redwood seedling is just 18 months old. Given 500 years or so, it’s going to get a wee bit bigger: The seeds of redwoods are absolutely titchy, as you can’t see in …

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The Michaelis-Menten model is not applicable to most enzymes in a cell

Sigmoidal kinetics [CC-BY-SA-3.0 Steve Cook]

Enzymes in cells can be modelled using the Michaelis-Menten model Enzymes can be, and often are, modelled by the Michaelis-Menten (well, Briggs-Haldane) model: v = vmax · [S] / (KM + [S]) Where: v is the velocity of the enzyme, which is the rate at which product accumulates vmax is the maximum velocity of the enzyme (i.e. …

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Enzymes don’t necessarily increase the rate at which products are formed

An enzyme increases the rate of product formation What happens if you add the enzyme malate dehydrogenase to a mixture of of its substrates NAD and malate (both at 1 mM for the sake of argument)? A brief look on BRENDA indicates that the reaction malate dehydrogenase catalyses is: malate + NAD → oxaloacetate + …

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Obfuscated pancakes

Anything is better than an recipe that uses volume measurements for highly compressible powders. I’m looking at you America, and your ridiculous ‘cup’ nonsense. Materials 0.110 kg powdered wheat endosperm (without added carbonates or tartrates) 4.28 mmol NaCl 2 unfertilised jungle-fowl eggs (between 63 and 73 g in mass) 275 mL of 75% (v/v) aqueous diluent …

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Educated guesswork

Enterobacter W1 [CC-BY-SA-3.0 Steve Cook]; cylindrical cells about a micron long

Someone recently asked me, “How many cells are there in the human body?” I have quite a lot of correspondence of this kind, just to be clear. I have to confess my first thought was “Not a bloody clue”. My second thought was “I bet the Internet knows”; but my third was “The Internet is full of …

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