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

Define solvent chemical potentials from phase equilibria, Define Solvent Ch...

Define Solvent Chemical Potentials from Phase Equilibria? Previously explained how we can evaluate the activity coefficient γ m,B of a nonelectrolyte solute of a binary soluti

Explain research dietitians, Explain Research dietitians Research diet...

Explain Research dietitians Research dietitians work in the field of normal or therapeutic nutrition Research dietitians seek ways to improve the nutrition of both  healthy

Gastric mucosa protected from the acid ph of the stomach, Q. How is the gas...

Q. How is the gastric mucosa protected from the acid pH of the stomach? The gastric epithelium is mucus secretory that is it produces mucus, the mucus covers the stomach wall p

What is vascular cambium? what are their functions?, What is vascular cambi...

What is vascular cambium? What are their functions? The Vascular cambium is the secondary meristematic tissue that in roots and in the stem forms the vascular tissues phloem an

How to investigate mitral regurgitation by electrocardiogram, Q. How to Inv...

Q. How to Investigate mitral regurgitation by Electrocardiogram? Patients with severe mitral regurgitation often have atrial fibrillation. Left atrial enlargement is a common f

Skin, physiology of skin

physiology of skin

What is allantois, What is Allantois One of the extraembryonic eggs foun...

What is Allantois One of the extraembryonic eggs found in the amniote animals. The allantois contains the metabolic wastes created by the developing embryo. May also be involved

Cranial nerves, The cranial nerves are composed of twelve pairs of nerves...

The cranial nerves are composed of twelve pairs of nerves which emanate from the nervous tissue of brain. In order to reach their targets they should ultimately exit/enter the cr

Congestive heart failure, In native-valve IE, acute CHF occurs more frequen...

In native-valve IE, acute CHF occurs more frequently in aortic-valve infections (29 per cent) than with mitral (20 per cent) or tricuspid disease (8 per cent). CHF may develop acut

Determine the isotopes of uranium and thorium, Does radioactive dating with...

Does radioactive dating with isotopes of uranium and thorium provide an estimate of the starting, middle, or end of the period of Earth's formation? Explain your answer No, th

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