Complex sentence: Holliday's original model assumed that heteroduplex DNA would be presence on both chromosomes, but experimental data on yeast refuted this, leading to an updated model by Matt Meselson and Charley Radding in 1975, which introduced the idea of the branch migration.
Split into simpler sentences: Holliday's original model assumed that heteroduplex DNA would be present on both chromosomes, but experimental data on yeast refuted this. An updated model by Matt Meselson and Charley Radding in 1975 introduced the idea of branch migration.