Not satisfied with textbook explanation of X chromosome deactivation

In summary, calico cats get their unique fur color from the random deactivation of one of their X chromosomes during embryo development. This process results in patches of fur with either the maternal or paternal X chromosome color only, as the daughter cells inherit the same X chromosome inactivation as their parent cell. This explains why there are black and yellow patches on calico cats, as the cells in each patch can be traced back to the same progenitor cell in the embryo.
  • #1
1MileCrash
1,342
41
According to my biology textbook, calico cats get their fur color mosiac from the random deactivation of one of their X chromosomes, by condensing them into barr bodies and displaying either the maternal or paternal X chromosome fur color only. IE each cell randomly deactivates either X and displays the remaining phenotype.

If this deactivation were truly random, why would their be black and yellow "patches" of fur on the cat? If it were truly random, and each had an equal chance, I would expect a cat that almost consisted of one fur color to the human eye because of an equal distribution and number of cells that deactivated maternal vs. paternal X and vice versa.
 
Physics news on Phys.org
  • #2
The x-chromosome inactivation occurs during the development of the embryo when not all the cells are finished dividing. Because x-chromosome inactivation is passed onto the daughter cells after cell division (e.g. the daughter cells will have the same x-chromosome inactivated as the parent cell), all the cells derived from that progenitor cell will have the same x-chromosome inactivated and have the same color. Thus, all the cells in one patch can trace their lineage back to the same cell in the embryo.
 

Related to Not satisfied with textbook explanation of X chromosome deactivation

1. What is X chromosome deactivation?

X chromosome deactivation, also known as Lyonization, is a process in which one of the two X chromosomes in female cells is inactivated. This is necessary because females have two X chromosomes, while males have one X and one Y chromosome. Without deactivation, females would have twice the amount of X chromosome gene products as males, which could lead to health problems.

2. Why is the textbook explanation of X chromosome deactivation not satisfactory?

The textbook explanation of X chromosome deactivation is often oversimplified and does not fully explain the complex mechanisms involved. It also does not mention the role of XIST gene, which is responsible for initiating the inactivation of one X chromosome.

3. How does X chromosome deactivation occur?

X chromosome deactivation occurs during early embryonic development in females. The XIST gene on one of the X chromosomes produces a long non-coding RNA that coats the entire chromosome, leading to its inactivation. This process is regulated by other factors and can differ between different cell types.

4. Does X chromosome deactivation affect all cells in the body?

Yes, X chromosome deactivation occurs in all cells except for the cells in the ovaries. This means that the inactivated X chromosome in one cell may be different from the one in another cell, resulting in a mosaic pattern of gene expression in females.

5. Is X chromosome deactivation reversible?

No, X chromosome deactivation is a permanent process and cannot be reversed. The inactivated X chromosome remains inactive throughout the lifetime of the cell. However, in some rare cases, the inactivation can be reversed in specific cells, leading to genetic disorders such as Turner syndrome.

Similar threads

  • Quantum Physics
Replies
16
Views
2K
  • Programming and Computer Science
Replies
1
Views
1K
  • Precalculus Mathematics Homework Help
Replies
8
Views
2K
Replies
3
Views
3K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
3K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
2
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
2
Views
3K
Back
Top