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 sanitation in food service establishments, Q. What is Sanitation in...

Q. What is Sanitation in food service establishments? We start our study of this topic by first defining what is sanitation? A three-word definition of food sanitation

Explain composition of human milk, Explain Composition of Human Milk? R...

Explain Composition of Human Milk? Research clearly shows that each type of mammalian milk is unique and consists of a highly complex mixture of organic and inorganic compounds

Transcription of a eukaryotic protein-coding gene, 1. Describe how the vari...

1. Describe how the various molecular mechanisms act to regulate transcription of the genes within the lactose operon of E. coli . 2. Transcription of a eukaryotic protein-codi

What is phagocytosis , Phagocytosis is the ingestion of huge particles ...

Phagocytosis is the ingestion of huge particles like as bacteria and cell debris by large endocytic vesicles called as phagosomes.   In order to be ingested the particle must first

Procedure for nelson somogyi method for glucose estimation, Explain Procedu...

Explain Procedure for nelson somogyi method for glucose estimation? Carry out the procedure following the steps enumerated herewith: 1. Label a series of  Folins tubes as bl

Nerve impulse, NE R VE IMPULSE (IT'S GENERATION) - It is an electr...

NE R VE IMPULSE (IT'S GENERATION) - It is an electro chemical phenomenon manifested through ionic movement across cell membrane. It was discovered by A. L. Hodykin & A

Explain the differance between savanna and desert, Explain the differance b...

Explain the differance between savanna and desert? Savanna : Savanna is characterized by relatively low rainfall and pronounced dry seasons. This type of climate produces a b

Bacteria is an obligate anaerobe, Q. What is signifying when it is said tha...

Q. What is signifying when it is said that a bacteria is an obligate anaerobe? Obligate anaerobes are those living beings that do not survive in the presence of oxygen. For exa

Explain cell cycle , The life of a eukaryotic cell can be explained ...

The life of a eukaryotic cell can be explained as a cell cycle. Mitosis and cell division happens in the M phase that lasts for only about 1 h. This is followed by the G1 phase whe

Why the ph of urine can be quite variable, The ph of urine can be quite var...

The ph of urine can be quite variable. Why? Why is bromothymol blue used as a ph indicator instead of phenal red when titrating blood?

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