Barr Body: Difference between revisions
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Since females posses two X chromosomes and males have one X chromosome and a [[Y chromosome|Y chromosomes]], Barr bodies are essential to regulate the amount of X-linked gene product being transcribed. To ensure that X-linked gene product doses are kept similar between males and females, one of the [[X chromosome|X chromosomes]] in a female becomes very condensed - the Barr body. This results in the genetic information on the chromosome being inaccessible to proteins that cause [[Gene|gene]] transcription. This is called [[Dosage Compensation Mechanism|dosage compensation]]. | Since females posses two X chromosomes and males have one X chromosome and a [[Y chromosome|Y chromosomes]], Barr bodies are essential to regulate the amount of X-linked gene product being transcribed. To ensure that X-linked gene product doses are kept similar between males and females, one of the [[X chromosome|X chromosomes]] in a female becomes very condensed - the Barr body. This results in the genetic information on the chromosome being inaccessible to proteins that cause [[Gene|gene]] transcription. This is called [[Dosage Compensation Mechanism|dosage compensation]]. | ||
[[X_chromosome_Inactivation]] is random and occurs at an early point of development. | |||
The number of Barr bodies in a cell is one less than the number of X chromosomes. For example: | The number of Barr bodies in a cell is one less than the number of X chromosomes. For example: | ||
Revision as of 20:25, 12 November 2012
A Barr Body is an inactivated, condensed X chromosome found in female cells.
Since females posses two X chromosomes and males have one X chromosome and a Y chromosomes, Barr bodies are essential to regulate the amount of X-linked gene product being transcribed. To ensure that X-linked gene product doses are kept similar between males and females, one of the X chromosomes in a female becomes very condensed - the Barr body. This results in the genetic information on the chromosome being inaccessible to proteins that cause gene transcription. This is called dosage compensation.
X_chromosome_Inactivation is random and occurs at an early point of development.
The number of Barr bodies in a cell is one less than the number of X chromosomes. For example:
- In a normal female with the genotype 46XX , the number of Barr bodies would be 1.
- In a normal male with the genotype 46XY, the number of Barr bodies would be 0.
However in a male with Klinefelter's syndrome (where the genotype is 47XXY), the number of Barr bodies would also be 1[1][2].