... response. Bacterial cells achieve motility via the utilisation of specialised structures known as flagella. Similar in structure to spinning tails, these flagella allow the bacterium to show both positive and negative chemotactic responses, based upon the presence of chemotactic molecules. The fine structure of the flagellum is that of a right-handed helical fibre embedded in the bacterial cell membrane. It is composed of multiple repeats of a single type of protein subunit called Flagellin. A single bacterial cell may possess multiple flagella. The bacterial flagellum sits between the inner and outer membranes of the bacterium, and has a number of distinct components. Rotation of the flagellum follows as a direct result of its structure. The fibre is connected by a short flexible protein hook to a small protein disc embedded in the plasma membrane. This disc constitutes part of the motor, and by utilising the energy stored in the transmembrane proton ...

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