What is a Barr body, and where is it found in a cell?
Transcribed text From Image: What is a Barr body, and where is it found in a cell? Select all that apply The number of Barr bodies per cell is always equal to the number of Y chromosomes present. O There will be one less Barr body than the number of X chromosomes It is a darkly stained region near the nuclear envelope of interphase cells It is an inactivated X chromosome It is the same X chromosome in every cell It is an inactivated Golgi complex in mammalian cells O The number of Barr bodies per cell is always equal to half the number of X chromosomes present. It is seen in nuclei of mammals with two or more X chromosomes O It is an inactivated Y chromosome It is seen in nuclei of mammals with two or more Y chromosomes O It is a darkly stained region in the cytoplasm, near the nuclear envelope Submit Previous Answers Request Answer X Incorrect; Try Again; 3 attempts remaining
Expert Chegg Question Answer:
BARR BODY: A Barr body is the inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X. It is named after discoverer Murray Barr. The Lyon hypothesis states that in cells with multiple X chromosomes, all but one are inactivated during mammalian embryogenesis. This happens early in embryonic development at random in mammals, except in marsupials and in some extra-embryonic tissues of some placental mammals, in which the father’s X chromosome is always deactivated. Mammalian X-chromosome inactivation is initiated from the X inactivation center or Xic, usually found near the centromere. The center also appears to be important in chromosome counting: ensuring that random inactivation only takes place when two or more X-chromosomes are present. The provision of an extra artificial Xic in early embryogenesis can induce inactivation of the single X found in male cells.
LOCATION: The inactivated X chromosome typically replicates later than other chromosomes, and it physically condenses to form a Barr body, a small structure found at the rim of the nucleus in female somatic cells between divisions.
A genotypical human female has only one Barr body per somatic cell, while a genotypical human male has none.
1. No. of barr bodies/cell = no. of Ychromosomes. NOT TRUE
2. There is one less barr body than no. chromosomes. TRUE
3. Dark stained region, near nucler envelope, interphase cells. TRUE
4. It is inactivated X chromosome.TRUE
5.It is inactivated golgi complex. NOT TRUE
6.No. of barr bodies per cell is always equal to half the no. of X chromosomes present. NOT TRUE
7. It is seen in nuclei of mammals with two or more X chromosomes. TRUE
8. It is inactivated Y chromosome. NOT TRUE
9. seen in nuclei of mammals with two or more Y chromosomes. NOT TRUE
10. Dark stained region in cytoplasm, near nucler envelope.NOT TRUE