Final answer:
Eliminating the XIST gene products with siRNAs would prevent X inactivation, which is necessary for dosage compensation in female mammals.
Step-by-step explanation:
The effect of adding small interfering RNAs (siRNAs) that eliminated the products of the XIST gene would be to prevent X inactivation.
XIST RNA is essential for the Barr body formation, which is the visible representation of the inactive X chromosome in female mammals.
By coating the X chromosome, XIST RNA triggers a series of epigenetic modifications that lead to the silencing of gene expression.
These epigenetic modifications include the methylation of DNA and hypo-acetylation of histones, which cause the nucleosomes to pack more tightly together, thus inactivating the chromosome.
Without XIST RNA, these modifications would not occur, and the X chromosome would remain active, leading to a failure in dosage compensation and potentially causing genetic imbalances.
In conclusion, XIST and associated factors are vital for ensuring the correct regulation of gene expression through the inactivation of one of the X chromosomes in female cells, avoiding the deleterious effects that could arise from having a double genetic dose of the X chromosome.