Final answer:
Dosage compensation is the process by which organisms balance gene expression between the sexes, with X inactivation in mammals serving as a prime example. It allows for equal expression despite the genetic differences between males and females.
Step-by-step explanation:
The process by which organisms equalize the expression of genes between members of different biological sexes is known as dosage compensation. This biological mechanism aims to balance the dose of X chromosome genes between females (XX) and males (XY). Dosage compensation is critical for developing organisms, as it ensures that neither sex has a significant advantage or disadvantage when it comes to gene expression from the sex chromosomes.
In mammals, one well-studied example of dosage compensation is X inactivation. During early embryonic development of female mammals, one of the two X chromosomes in each cell condenses into a dormant structure known as a Barr body. The inactivation of one X chromosome allows for the levels of X-linked gene expression to be similar between males and females, preventing an overdose of these genes in females.
Another form of dosage compensation can be observed in organisms that utilize different mechanisms, such as genetic- and temperature-dependent sex determination. Some species even change their biological sex during their lifespan, a process known as sequential hermaphroditism, which includes protogyny and protandry in species like oysters.