Final answer:
Dosage compensation in fruit flies is achieved by hyperactivating the single X chromosome in males, equalizing gene expression with females who have two X chromosomes.
Step-by-step explanation:
Dosage compensation in fruit flies is achieved through the process of hyperactivation of the single X chromosome in males to balance the gene expression with females, who have two X chromosomes. Unlike in humans, where one of the two X chromosomes in females is inactivated to become a Barr body, fruit flies use a different mechanism to ensure that the expression of genes on the X chromosome is equivalent in both sexes.
This mechanism involves the upregulation of the single X chromosome in male flies (XY) to match the output from the two X chromosomes in female flies (XX). Genetic regulation ensures that males do not have fewer X chromosome gene products than females, maintaining a balance in gene expression necessary for proper development and cellular function. The principle behind dosage compensation is critical, as it ensures that organisms like Drosophila melanogaster maintain the correct gene expression levels despite the difference in chromosome number between the sexes.