plural ; com·ple·men·tar·i·ties
: correspondence in reverse of part of one molecule to part of another: as a : the arrangement of chemical groups and electric charges that enables a combining group of an antibody to combine with a specific determinant group of an antigen or hapten b : the correspondence between strands or nucleotides of DNA or sometimes RNA that permits their precise pairing <evolution of the contemporary genetic code involving purine-pyrimidine complementarity—Struther Arnott & P. J. Bond>
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