Final answer:
Gene loss depends on which genes were lost. Changes in genes can occur through various mechanisms, including deletion of a segment of DNA, inactivation of genes associated with pathogenicity, or turning off genes through epigenetic modifications.
Step-by-step explanation:
Gene loss depends on which genes were lost. Changes in genes can occur through various mechanisms, including deletion of a segment of DNA, inactivation of genes associated with pathogenicity, or turning off genes through epigenetic modifications. For example, in cancer cells, alteration to epigenetic modifications turns off genes that are normally expressed.