What is the function of Chromocenter?
Structures known as chromocenters, comprising satellite DNA and proteins such as D1 or HMGA1, help to contain DNA inside the nucleus between cell divisions.
Where do you find chromocenter?
Within many organisms centromeres, pericentromeric heterochromatin and in some cases even telomeres cluster to form a nuclear domain or aggregate called chromocenter (24). These aggregates are frequently found at the nuclear periphery or around the nucleolus.
What is Chromocenter in polytene chromosome?
As the polytene chromosomes, the centromeres of all chromosomes normally aggregate to form a chromocenter that consists largely of heterochromatin. The remaining ~ 75% of the genome is organized into alternating bands and interbands in the polytene chromosome.
What are Balbiani rings?
Balbiani rings are exceptionally large puffs on the polytene chromosomes in the dipteran Chironomus tentans. These puffs are particularly well suited for studies of the structure of active genes and the synthesis and transport of specific RNA-protein (RNP) particles.
Where are Balbiani rings?
Balbiani rings are sites of particularly active RNA synthesis on the polytene chromosomes of Chironomids. Three such sites occur on the fourth chromosome in the salivary glands of Chironomus tentans.
Who discovered Balbiani rings?
The hereditary nature of these structures was not confirmed until they were studied in Drosophila melanogaster in the early 1930s by German biologists Emil Heitz and Hans Bauer. In 1930, Heitz studied different species of Drosophila (D. melanogaster, D. simulans, D.
Is satellite a DNA?
Satellite DNA (satDNA) is the highly repetitive DNA consisting of short sequences repeated a large number of times. It carries a variable AT-rich repeat unit that often forms arrays up to 100 Mb. The monomer length of satDNA sequences ranges from 150 to 400 bp in the majority of plants and animals.
What is the largest gene?
The largest known gene is the human dystrophin gene, which has 79 exons spanning at least 2,300 kilobases (kb).
What is mean by Balbiani rings?
What is highly repetitive DNA?
Repetitive DNA: DNA sequences that are repeated in the genome. These sequences do not code for protein. One class termed highly repetitive DNA consists of short sequences, 5-100 nucleotides, repeated thousands of times in a single stretch and includes satellite DNA.
What is the shortest human gene?
Chromosome 21 is the smallest human chromosome, spanning about 48 million base pairs (the building blocks of DNA) and representing 1.5 to 2 percent of the total DNA in cells.
Where can I find the definition of chromocenter?
Also found in: Dictionary, Encyclopedia . A mass of chromatin often found in the interphase cell nucleus representing a more condensed zone of chromatin filaments. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, or visit the webmaster’s page for free fun content . Mentioned in ?
How are whole chromosome domains arranged around the chromocenter?
Whole chromosome domains are arranged around the chromocenter, suggesting that the chromocenter is a central organizing structure that helps create a defined nuclear topology in spermatids ( Haaf & Ward, 1995; Meyer-Ficca et al., 1998 ).
What is the name of the heterochromatic region of chromosome?
Chromocenter. the heterochromatic region of a chromosome that retains the tightly spiralized structure of a chromonema between two successive cell divisions in the interphase. When stained with nuclear dyes, the chromocenter appears under the microscope to be a solid body. The size and number of chromocenters differ in the interphase nuclei…
How is a chromocenter formed in a Drosophila cell?
In Drosophila and in some other dipteran insects, a single large chromocenter is formed in cells with giant polytene chromosomes through the uniting of the centromere regions of all the chromosomes.