cos (redirected from Class of service)
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Abbreviation for Chief of Staff.
cos site the region formed when the COHESIVE ENDS of certain BACTERIOPHAGES, notably bacteriophage lambda, join together. A cos site is formed when the linear CHROMOSOME of bacteriophage lambda circularizes following infection of a host cell. Concatemeric (see CONCATEMER lambda DNA is cut at cos sites when the DNA is packaged during phage assembly in the LYTIC CYCLE.