Microtubules (Term Paper Sample)

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Microtubules
Microtubules are intracellular filamentous structures that aid in that is responsible for eukaryotic cells’ movement. They are also involved in cell division, intracellular transport, and intracellular structure organization. They also help in cilia and flagella motility. In maintaining their tubular form, microtubules have both horizontal and longitudinal interactions stuck between tubulin subunits. The subunits are linked from head to tail to form a proto-filament through longitudinal interactions between adjacent subunits. Dimeric subunits reiterate every 8 nm within each protofilament. These proto-filaments in turn interact side by side forming a sheet of the microtubule. Research is, however, ongoing on the precise proto-filaments arrangements on microtubule walls. In some cases, heterodimers in proto-filaments next to each other form α-tubulin and β-tubulin monomers in the microtubule wall or sometimes the subunits stagger to produce a checkerboard shape of the microtubule (Arunabha, et al., 2014).
In unicellular eukaryotes and bacteria, flagella allow bacterial cells to traffic searching for food as well as a conducive environment. Nevertheless, functional specifics of bacterial flagella greatly vary from the ones exhibited by eukaryotic flagella forms. The bacterial flagellum filament is joined via a hooked fragment to some proteins that produce a rotating force. This minute motor revolves the whole filament that helps move bacteria the same way a motor boat propeller moves it in water. The specialized flagella permit bacteria to decide on whether to go forward or backward in response to stimuli or search for food by altering the rotation direction of the flagellum. They can as well allow for swarming motility that is a coordinated collective movement and tumbling that is a slightly random rotation (Larsen et al., 2013).
Comparatively, cilia help microorganisms undertake numerous cellular functions that are important for the survival. Cilia are capable of moving the whole cell, but groups of cilia working together can produce steady water and mucus movement among other extracellular constituents. An example is the human respiratory tract that has special ciliated epithelial cells that work in connection with goblet cells in keeping lungs clean. Mucus secreted by goblet cells collects dust and foreign matters and ciliated cells, with the aid of cilia sweep the mucous off the lungs to avoid respiratory complications in the airways. The presence of abundant mucous flow always accompanying infectious diseases is an attempt by the body to exit pathogenic microorganisms as well as byproducts of toxic nature. In cases of severe diseases, excessive mucous is produced hence overpowering ciliated cells that lead to mucus accumulation in the airways (Reich and Jerome, 2014).
Kartagener syndrome refers to an inherited abnormal condition classified as an autosomal recessive feature. The disease is characteristic of cilia protein structure abnormalities, situs inverses, chronic sinusitis, and bronchiectasis. It is a primary ciliary dyskinesia whose symptoms vary ranging from neonatal respiratory distress, middle ear infections in early childhood stages and other minor signs. Gene mutations are the major causes and research is underway to ascertain the definite causes of particular cases. No known cure for this disease and treatment vary with indicative symptoms for Kartagener syndrome per an individual but mostly antibiotics as well as therapies involving airway clearance have been used (Reich and Jerome, 2014).
This syndrome is caused by defects in the dynein microtubule arms extending between axoneme microtubules. This leads to respiratory infections in which the cilia in the respiratory tract is unable to clear pathogenic bacteria and foreign matter. The disease also leads to male infertility as the sperms are unable to propel themselves to the ovum due to defective flagella. Smoking cigarettes is also a form of acquiring the disease rather than inherit it as tar and mucus build up in the lungs hence improperly removed as cilia are impaired by the cigar smoke. Therefore, other than the microtubule dysfunction, ...