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Tag Archives: Bacteria

Classification of Life: The Three Domain Concept

A domain is the highest taxonomic level of species in biology. In 1977, Woese and his coworkers developed the groundbreaking three-domain system.  They proposed this classification based on differences in the sequences of nucleotides in the cell’s ribosomal RNAs (known as 16S rRNA). They created the first worldwide tree of …

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Rickettsia: The Disease Causing Bacteria (Part-1)

‘Rickettsia’ is a genus of non-motile, gram-negative, non spore-forming, highly pleomorphic bacteria that may occur in the forms of cocci, rods, or threads. The term ‘rickettsia’ has nothing to do with ‘rickets’, which is a deficiency disease resulting from lack of vitamin D; the bacterial genus ‘Rickettsia’ was named after Howard Taylor …

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