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The fluid mosaic model describes the composition and function of cell membranes.  Membranes are made of lipids and proteins (and a few other bits and bobs but don’t worry about that here).  The lipids ...

A gene is a segment of DNA that carries the instructions for a specific trait, such as eye colour or how well you can digest food.  When DNA is damaged or is copied incorrectly this changes the gene an...

Saltatory conduction refers to the passage of an action potential along a myelinated neurone. Myelin is a lipid that forms a fatty sheath around the neurone axon and it is an electrical insulator. This me...

Fertilisers are generally high in nitrogen, to replenish the nitrogen in the soil assimilated by the crop plants. When this is drained into lakes in run-off, it can cause dramatic consequences. Nitroge...

Cholera is single-celled organism that produces a toxin. The toxin attaches to the ion receptors in the small intestine which causes it to secrete chloride ions into the lumen. This then causes water t...