Dosage compensation Mechanisms: X-Inactivation, X-Hyperactivation and X-Hypoactivation
Dosage compensation Mechanisms (X-Inactivation, X-Hyperactivation and X-Hypoactivation)
- Different mechanisms that are used by organism to adjust the unequal dosage of X-linked genes in males and females are know as dosage compensation
- Animal development is quite sensitive to an imbalance in the number of genes.
- Generally, each gene is present in two copies. Deviation from this condition, either up or down, can cause abnormal phenotypes, and sometimes even death.
- Why so many species should have a sex-determination system based on females with two X chromosomes and males with only one? In these species, how is the numerical difference of X-linked genes accommodated?
Three mechanisms may compensate for this difference
- One copy of each X-linked gene could be inactivated in females (X-Inactivation; eg human)
- Each X-linked gene could work twice as hard in males as it does in females (X-Hyperactivation eg drosophila)
- Each X-linked gene could work half as hard in females as it does in males (X-Hypoactivation eg., Caenorhabditis elegans
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