X-inactivation
X-inactivation
X-inactivation (pronunciation: eks-in-ak-ti-va-shun) is a process that occurs in female mammals where one of the two copies of the X chromosome present in each cell is inactivated. The process is also known as lyonization after the British geneticist Mary F. Lyon, who first proposed the theory in 1961.
Etymology
The term "X-inactivation" is derived from the process it describes, where one of the two X chromosomes in female mammals is inactivated. The term "lyonization" is named after Mary F. Lyon, who first proposed the theory.
Process
During X-inactivation, one of the two X chromosomes in each cell of a female mammal is randomly inactivated. This process begins early in embryonic development and continues throughout the life of the organism. The inactivated X chromosome condenses into a structure known as a Barr body.
Function
The primary function of X-inactivation is to balance the dosage of X-linked genes between males and females. Males have only one X chromosome, while females have two. Without X-inactivation, females would have a double dose of X-linked genes, which could lead to overexpression and potential health problems.
Related Terms
- Barr body: The inactivated X chromosome in a female cell.
- Dosage compensation: The process by which X-inactivation balances the expression of X-linked genes between males and females.
- XIST (gene): A gene on the X chromosome that plays a crucial role in X-inactivation.
- Mary F. Lyon: The British geneticist who first proposed the theory of X-inactivation.
External links
- Medical encyclopedia article on X-inactivation
- Wikipedia's article - X-inactivation
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