We all know that, living organisms includes microorganisms. Microorganisms are divided into different types like virus, bacteria, fungi etc... Flagellum is one of the part that belongs to bacteria. Their appearance will be like thread like appendages. Let's look into the flagellum topic in detail.
Flagellum and its type:
Flagellum protrude from the cell wall of bacteria. Also, they are composed of protein subunits. These subunits are called as flagellin. Flagellum helps in the locomotion of bacteria. Locomotion is the ability to move from one place to another with help of any part in the body. For human, we are moving by our legs. So, locomotion of human is legs. There is no single flagellum. There is a vast range of different flagella. A bacterium could arrange a single flagellum at one end called monotrichous or polar flagellum. There could be one flagellum on each end of the bacterium, called Amphitrichous. Several flagella could be clustered together on one end called lophotrichous.The flagella could be distributed all about the bacterium called Peritrichous.
Archaellum or archae flagellum:
Each domain has its own type of flagella. Bacteria have peptidoglycan in their walls, so bacterial flagella must be built to accommodate. Archae flagella called archae ella have quite few difference from bacterial flagella. For example, archaellum are powered by ATP. while bacterial flagella are powered by hydrogen ions. Archaellum grow by adding subunits to the base. While, bacterial flagella grow by adding them to the top. Bacteria flagella are thicker than archaellum. Eukaryotic flagella are composed of microtubules.
Evolution of flagellum:
Flagellum is an irreducible complex structure. Irreducible complex structure is a structure that cannot be reduced to constituent parts and remain functional. Anti evolutionists would argue that the flagellum in any form could not to be functional, if it evolved step by step through evolution. In bacteria, the flagellum is ultimately derived from type 3 secretion system, which is an appendage that allows bacteria to secrete proteins. Complex protein secretion system employed by many gram negative pathogenic bacteria. Transport bacterial effector proteins across three membrane barriers into eukaryotic host cytoplasm. The effector proteins that are delivered by TTSS are capable of modulating and interfering with the host cellular process, which is plague, Typhoid fever, even bacterial dysentery. Also, it is composed of more than twenty proteins along with effector proteins and chaperons. In archaellum, the flagellum share many similarities with the type 4 Pil A or hair like appendages found on many bacteria. In eukaryotes, it would appear like the flagellum which spread throughout the domain. Also, it is found that, formation of the bacterial flagellum could arise from a series of gene duplications and simple modification. Comparison of complete genome sequence of flagellated bacteria revealed that the flagellum is based on an Ancestral set of 24 core genes for which homologs are present in genomes of all bacterial phylum. So, from the analysis, it is found that these core genes originated from one and another through a series of duplications. And inference based on the fact, they still retain significant sequence homology close quote. In other words,The whole flagellum could ultimately be based on a single repeatedly duplicated gene. Experiments have revealed that mutating flagella can have significant effects. And in 2017, paper novel, genes associated with enhanced motility of Escherichia colli st 1 31. Researchers saw that certain mutations in the e colli gene EC 958 actually increased the motility of their flagellum. So, at last flagellum is not irreducible complex, it is very capably evolved from pre-existent structures.
Conclusion:
Flagellum is an interesting topic in bacterial concepts. As the evolution and functions differs from each other. Also, flagellum acts as locomotion for bacteria. So, this article clearly shows the evolution of flagellum.
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