Mitochondria and chloroplasts have small genomes because: Question 8 options: their bacterial ancestors did over time, much of their DNA has migrated to the host cell nucleus they lack most coding DNA the genes the need to function are shorter than eukaryotic genes their bacterial ancestors did over time, much of their DNA has migrated to the host cell nucleus they lack most coding DNA the genes the need to function are shorter than eukaryotic genes Solution Answer : The correct answer is A (their bacterial ancestors). Both mitochondria and chloroplasts are closely realed to prokaryotes and also lacks introns, which are the non coding sequences..