Consider this statement: \"Humans are much more able to tolerate missing a sex c
ID: 89101 • Letter: C
Question
Consider this statement: "Humans are much more able to tolerate missing a sex chromosome than they are able to tolerate missing an autosome ."
Conduct research to understand what a "Barr body" is. Do not submit an answer with a lot of scientific jargon. Using basic biology vocabulary, explain "Barr body" in your own words.
Respond directly to the statement above with regards to females.
Dr. Murray Barr (1908-1995), was a Canadian researcher who co-discovered Barr bodies. Some of the work he did involved studying coat (fur) colour in calico cats. Coat colour in these cats is determined by a sex-linked gene; but, it also involves Barr bodies. Using your knowledge of genetics, describe how calico cats get their colour. Compare male and female calico cats.
Explanation / Answer
Well actually the statement above is correct i.e. humans can tolerate extra sex chromosome than extra autosome. The ability of the humans to tolerate supranumerary sex chromosomes is remarkable. This tolerance relates to inactivation of both the X chromosomes and to a small number of genes on Y chromosome.
If we talk about the Barr Body; which is a small densely stained structure in the female somatic cells consisting of inactive X. Barr body is ragarded as the diagnostic of genetic femaleness.
The barr body appers when the cell with supranumerary copies of X are observed under microscope.
Now let us talk about the Calico cats which are the domestic cats with spotted coast that is predominantly white with the patches of two other colors (orange and black).
The determination of the coat color is linked to X chromosome. The calico cats are nearly females with one color linked to maternal X and one linked to the paternal X chromosome. The coat color is mainly due to X in activation involvng the random inactivation if ne of the X chromosome.
Males have one X chromosome and one Y. As males have only one X chromosome, it would have a rare condition where they have 3 sex chromosomes. In rare cases faulty cell division may leave an extra X chromosome in one of the games producing male cats.