Bacteria is an example of a unicellular prokaryote. Several bacteria move by turning the flagellum (Kojima, 2015). Several movable bacteria move in fluid or on a firm exterior utilising their flagellum. The flagellum has a spiral shape and expands from the cell body. The flagellum’s turning movement causes the bacterial cell to swim. The rotary motor located in the inner membrane and cell wall (cell envelope) operates the turning of the flagellum. The motor gets energy from the electrochemical gradient of the ions flowing across the membrane. The majority of neutrophiles obtain energy from the electrochemical gradient of hydrogen ions and sodium ions for some alkaliphiles.
The motor of the flagellum is made up of the rotor and about twelve stator components encircle every rotor (Kojima, 2015). The rotor stator mechanism combined with the movement of the ions that pass the channel located in the stator creates rotational force and thus electrochemical energy is changed into mechanical energy by the stator. E-coli is an example of a bacteria that uses flagella to move (Ni et al.,2017). In e-coli, the genes belonging to the flagella are grouped together depending on their sequence of expression and the regulation of transcription. This encodes for greater than forty proteins that are vital for the movement of the flagella.
In unicellular eukaryotes, the flagella are made from a centre of microtubules with a membrane encircling it (Rathinam and Sverchkov, 2018). The centre of microtubules is a set of microtubules in the middle encircled with nine pairs of microtubules. The movement of particles in the flagellum between the centre of the microtubule and the membrane are in charge of conveying proteins that are necessary for the growth of the flagella. The flagella beat repeatedly in a eukaryotic cell (Shingyoji, 2018). The arrangement of dynein proteins on the pair of microtubules are in control of the movement of the flagella. Using energy given off during hydrolysis of ATP, dynein transfers the neighbouring pairs of microtubules towards the end of the flagella away from the centre of the body. The sliding power produced by dynein is used to move the flagellum in a curving wave like manner. Dynein activity is split into four stages (Shingyoji, 2018).
The essential ATP-operated force creation of the dynein arms is the first stage. The second stage is the sliding of dynein arms located along every pair of microtubules. The third stage is the modulation of the sequence of sliding about the axonemal axis. The fourth stage is the start of the beating of the flagella along with mechanical power of bending. Chlamydomonas reinhardtii, green algae, is an example of a eukaryote that uses two flagella to swim (Geyer et al., 2016). The direction of movement is regulated by the static part and the momentum is produced by the dynamic part.
- Kojima, S., 2015. Dynamism and regulation of the stator, the energy conversion complex of the bacterial flagellar motor. Current Opinion in Microbiology [online]. 28, pp.66-71. [viewed on 2 October 2020]. Available from: https://www-sciencedirect-com.ezproxy.lib.gla.ac.uk/science/article/pii/S1369527415001320?via%3Dihub
- Ni, B., Ghosh, B., S.Paldy, F., Colin, R., Heimerl, T. and Sourjik, V., 2017. Evolutionary Remodelling of Bacterial Motility Checkpoint Control. Cell Reports [online]. 18(4), pp.866-877. [viewed 2 October 2020]. Available from: https://www.sciencedirect.com/science/article/pii/S2211124716318101#!
- Rathinam,M., Sverchkov, Y., 2018. Stochastic Dynamics of Eukaryotic Flagellar Growth. Bulletin of Mathematical Biology [online]. 81, 2849-2872. [viewed 3 October 2020]. Available from: https://link-springer-com.ezproxy.lib.gla.ac.uk/article/10.1007%2Fs11538-018-0427-1#citeas
- Shingyoji, C., 2018. 11- Regulation of dynein-driven ciliary and flagellar movement. Dyneins: Structure, Biology and Disease (Second Edition) [online]. 1, pp.336-367. [viewed 3 October 2020]. Available from: https://www.sciencedirect.com/science/article/pii/B9780128094716000115
- Geyer, V., Sartori, P., Friedrich, B., Jülicher, F., Howard, J., 2016. Independent Control of the Static and Dynamic Components of the Chlamydomonas Flagellar Beat. Current Biology [online]. 26(8), pp.1098-1103. [viewed 3 October 2020]. Available from: https://www-sciencedirect-com.ezproxy.lib.gla.ac.uk/science/article/pii/S096098221630135X?via%3Dihub