Facts about bacterial genomics

• complete genome sequences have been obtained for many organisms of medical significance

• there is relatively little non-coding DNA; introns are largely absent

• genes in bacteria are clustered according to biochemical function and transcribed as a unit termed an operon

• there are many operons that regulate and produce enzymes with specific biochemical functions

• genes for essential structures and metabolic functions are arranged in a relatively constant order characteristic of a species. the arrangement of genes around the chromosome varies a significant amount between bacteria that are unrelated, but is relatively constant between bacteria of the same species

• many bacteria have a large number of phage and phage remnants in their genomes, and these differ in individual strains of a species. the core genes may be the same, but there may be major differences in the chromosome where phage and phage remnants have inserted and left

• strains of a species may also differ by many insertions and deletions of both small and large DNA segments

Category: Microbiology Notes