What is barr body genes, Biology

Assignment Help:

Q. What is Barr body Genes?

Located inside nuclear envelope, it's a densely staining object which is an inactivated X chromosome in female mammalian cells. Most Barr body genes aren't expressed. They are reactivated in gonadal cells that undergo meiosis to form gametes. Female mammals are a mosaic of two different types of cells, those with an active maternal X and those with an active paternal X. Which of the two Xs will be inactivated is concluded randomly in embryonic cells. After an X is inactivated, all mitotic descendants will have same inactive X. As a consequence, if a female is heterozygous for a sex-linked trait, about half of her cells will express one allele and the other cells well express alternate allele. Illustrations of this type of mosaicism are coloration in calico cats and normal sweat gland development in humans. A woman who is heterozygous for this trait has patches of skin and patches of skin lacking sweat glands. X chromosome inactivation is related with DNA methylation. Methyl groups (-CH3) attach to cytosine, one of DNA's nitrogenous bases. Barr bodies are highly methylated compared to actively transcribed DNA. What determines which of two X chromosomes would be methylated? - A newly discovered gene, XIST is active only on the Barr body. Product of the XIST gene, X-inactive specific transcript, is an RNA; multiple copies of XIST attach to X chromosome inactivating it.


Related Discussions:- What is barr body genes

What is paediatric clinical literature, What is paediatric clinical literat...

What is paediatric clinical literature The paediatric clinical literature has expanded greatly in its coverage of the wide variety of medical circumstances that can negatively

What are the types of chronic gastritis, Q. What are the types of chronic g...

Q. What are the types of chronic gastritis? Gastroscopic observation shows different types of chronic gastritis: 1. Superficial gastritis: gastric mucosa is red, oedematous,

Classification of living organisms – species, Classification of Living Orga...

Classification of Living Organisms – Species You have by now already come across the word 'species'. The word has a definite meaning in biology. Although the living world is v

Philum colenterata, What are the economic importance of colenterata

What are the economic importance of colenterata

What is respiratory system explain their functionality , What is Respirator...

What is Respiratory System explain their functionality ? The respiratory system is responsible for the transport of oxygen and carbon dioxide from outside the body to and from

#title.humans and environment., what are the two main pollutants that contr...

what are the two main pollutants that contribute to aci rain

Horse diseases-equine infectious anaemia, Equine infectious anaemia Eq...

Equine infectious anaemia Equine infectious anemia (EIA), an acute or chronic viral disease of the equines, shows intermittent fever, loss of weight, depression, progressive w

Define protein requirement during tuberculosis, Define Protein requirement ...

Define Protein requirement during tuberculosis Protein : Achronic infection  is marked by a prolonged duration of fever. This leads to wasting of muscles, increased nitrogen

Disbeliefs about insulin injection, Some people have disbeliefs regarding i...

Some people have disbeliefs regarding insulin injection. You have to find out if there are any disbeliefs and try to explain the importance of insulin injection. Do not force the p

Horse diseases-african horse sickness, African horse sickness African h...

African horse sickness African horse sickness (AHS) is a highly fatal insect born viral disease of equidae caused by an Orbivirus (family Reoviridae) and characterized by sever

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd