May 2013 archive

Organism of the week #14 – Turtles all the way down

Kryptoperidinium [CC-By-SA-3.0 Steve Cook]

Cassiopea, which looks rather like a spelling mistake (but isn’t), also looks a bit like an anemone (but isn’t): It’s actually a jellyfish, but one that spends most of its time living upside-down (relative to its relatives). Unlike its close relatives, it gets much of its energy from sunbathing rather than from fishing. Inside the cells …

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Organism of the week #13 – Unlucky for some

Datura metel (flower) [CC-BY Alex Lomas]

I’m a sucker for things that are both poisonous and pretty. Datura metel definitely meets both criteria. These photos were taken in southern Spain, where this purple variety of the plant seemed to have naturalised itself out from someone’s garden . Datura metel is closely related to Atropa belladonna, the deadly nightshade, and – like it …

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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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