Navigation Links
Centromere


The centromere is a region of a eukaryotic chromosome where the kinetochore is assembled. Thus, it is the site where spindle fibers of the mitotic spindle attach to the chromosome during mitosis. It is also the site of the primary constriction visible in microscopy images of chromosomes.

In most eukaryotes, the centromere has no defined DNA sequence. It typically consists of large arrays of repetitive DNA where the sequence within individual repeat elements is similar but not identical. In humans, the centromeric repeat unit is called α-satellite. However, repeats of α-satellite are not sufficient to cause the assembly of a kinetochore, and there are functioning centromeres with no α-satellite DNA.

Epigenetic inheritance plays a major role in specifying the centromere in most organisms. The daughter chromosomes will assemble centromeres in the same place as the parent chromosome, independent of sequence. However, there must still be some original way in which the centromere is specified, even if it is subsequently propagated epigenetically. In rare cases in humans, neocentromeres can form at new sites on the chromosome. This must be coupled with the inactivation of the previous centromere since chromosomes with two functional centromeres (dicentric chromosomes) will result in chromosome breakage during mitosis.

The centromeric DNA is normally in a heterochromatin state, which is probably essential for its function. In this chromatin, the normal histone H3 is replaced with CENP-A, a centromere-specific variant. The presence of CENP-A is believed to be important for the assembly of the kinetochore on the centromere and may play a role in the epigenetic inheritance of the centromere site.

In the yeast Schizosaccharomyces pombe (and likely in other eukaryotes) the formation of centromeric heterochromatin is connected to RNAi*. In nematodes such as Caenorhabditis elegans and in some plants, chromosomes are "holocentric" indicating that there is not a primary site of microtubule attachments or a primary constriction, and a "diffuse" kinetochore assembles along the entire length of the chromosome.

See also: Genetics -- Cell biology

External links


'"/>


(Date:4/27/2015)... Fla. , Apr. 27, 2015 Profile ... access control and security systems is pleased to announce ... company as a consultant and member of its scientific ... is widely known as a thought leader in technology-enhanced ... Learning Technology Group, and has published studies and books ...
(Date:4/17/2015)... Increasing adoption in ... to drive biometric systems market in ... According to a recently released TechSci Research ... biometric systems market in Saudi Arabia ... CAGR of over 22% through 2020. The market ...
(Date:4/13/2015)... April 13, 2015  higi, a leading cloud-based consumer ... more fully engage with their communities around health and ... protected and secure API.  ... most accessible, affordable, and convenient vehicle to receive validated ... The API will allow higi,s trusted ...
Breaking Biology News(10 mins):Profile Solutions Names Medicinal Cannabis, Agriculture and Technology Expert Dr. Gerry Bedore to its Scientific Advisory Board 2Profile Solutions Names Medicinal Cannabis, Agriculture and Technology Expert Dr. Gerry Bedore to its Scientific Advisory Board 3Profile Solutions Names Medicinal Cannabis, Agriculture and Technology Expert Dr. Gerry Bedore to its Scientific Advisory Board 4Saudi Arabia Biometric Systems Market to Grow at 22% Through 2020, Says TechSci Research 2Saudi Arabia Biometric Systems Market to Grow at 22% Through 2020, Says TechSci Research 3higi Launches Seamless Access to HIPAA-Compliant Health Outcomes and Activity Data 2higi Launches Seamless Access to HIPAA-Compliant Health Outcomes and Activity Data 3
... basic scientists and clinicians have an interest in how the ... order for organisms to grow, to heal, to transmit information ... of other activities necessary for survival. But if cell mobility ... A new multi-disciplinary study by University of Pennsylvania researchers ...
... Vision licensee, Theresa Ayers , has added a second location ... Ronald Ayers , the husband-and-wife team assumed ownership last month ... Theresa Ayers has been with Pearle Vision, one of ... for more than three decades. She began her career working for ...
... for Biotechnology and Medical Genomics announced four research ... Transformation Grant Program. Together, the selected researchers were ... their work in diabetes research. Minnesota Partnership funding ... With an eye on funding projects with ...
Cached Biology News:Multi-disciplinary Penn research identifies protein required for cell movement 2Multi-disciplinary Penn research identifies protein required for cell movement 3Local Pearle Vision Licensee Adds Second Center In Canton, Ohio 2Local Pearle Vision Licensee Adds Second Center In Canton, Ohio 3Local Pearle Vision Licensee Adds Second Center In Canton, Ohio 4Local Pearle Vision Licensee Adds Second Center In Canton, Ohio 54 projects awarded Discovery Transformation Grant funding by Minnesota Partnership 24 projects awarded Discovery Transformation Grant funding by Minnesota Partnership 3
Other biology definitionOther Tags