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

Which blood vessels carry venous blood to the heart, Q. What are the blood ...

Q. What are the blood vessels that carry venous blood to the heart? What is the blood vessel that collects arterial blood from the heart? The blood vessels that debouch in the

Types of nitrogen wastes excreted by living beings, Q What are the three ma...

Q What are the three major types of nitrogen wastes excreted by living beings? The main nitrogen wastes excreted by living beings are ammonia, urea and uric acid. Living beings

Louping ill, Louping ill This is an infectious encephalomyelitis of sh...

Louping ill This is an infectious encephalomyelitis of sheep and man occurring during spring and summer when the vectors like ticks are active. It is reported from British Isl

Define resolution - terminologies used in chromatography, Define Resolution...

Define Resolution - terminologies used in chromatography? Resolution is the effectiveness of the separation and is determined by two factors. These include: Distance

What would its new ph be if the concentration of h3o ion, If a solution has...

If a solution has a pH of 7.5, what would its new pH be if the concentration of H 3 O ions in the solution were increased by 100 times? Explain your reasoning. As a tenfold inc

Molecular genetics and plant growth hormone, Molecular Genetics and Plant G...

Molecular Genetics and Plant Growth Hormone Molecular genetics has advanced over the last three decades by leaps and bounds, providing knowledge regarding the control of devel

What is the phase of the menstrual cycle, In general what is the phase of t...

In general what is the phase of the menstrual cycle when copulation may lead to fecundation? Although this is not a rule, to be effective fecundation in general must happen wit

Passage of pollen tube, Passage of Pollen Tube In cotton, the pollen p...

Passage of Pollen Tube In cotton, the pollen produces a tube within an hour which grows on the surface of the stigmatic hairs, and then between the cells of the stigma at the

Classification of enzymes, Classification of Enzymes : Enzymes are clas...

Classification of Enzymes : Enzymes are classified  into the following six main categories in according with  the nature of reaction the catalyze: 1.      Oxidoreductases

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