In a famous experiment, matthew meselson and franklin stahl grew e. coli cells in a medium containing only the "heavy" isotope of nitrogen, n15 . these cells were then transferred to a medium with the "light" isotope of nitrogen, n14 . the results of the experiment supported the hypothesis of semiconservative replication, which was proposed by watson and crick. heavy dna ( n15 dna), hybrid dna, and light dna ( n14 dna) can be separated by centrifugation. if cells containing n15 dna are transferred to a medium with only n14 nh4cl as a nitrogen source, what percent of daughter molecules are composed of hybrid dna after 3 generations?