Read Stable Lipid-Water Arrangements
A focused NSEB read for predicting stable arrangements of amphipathic lipids in water.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Follow head and tail chemistry
Phospholipids and similar amphipathic molecules have hydrophilic head groups and hydrophobic hydrocarbon tails. In water, head groups interact with water while tails avoid it. A micelle therefore presents heads outward and packs tails into the interior.
Recognise a stable aggregate
For the source diagram, structure A is the radial micelle-like arrangement with polar heads exposed and non-polar tails sequestered. Reversing the orientation exposes hydrophobic tails to water and is unstable. The same principle also underlies bilayers, though a bilayer has two leaflets rather than one radial aggregate.
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- ✓Hydrophilic head faces water.
- ✓Hydrophobic tail is shielded from water.
- ✓Micelle: heads outside, tails inside.
- ✓Bilayer: heads on both aqueous faces, tails at the centre.
A radial cluster is not automatically stable: check which chemical group faces water.
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