Centromere: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
A centromere is present before the [http://bms.ncl.ac.uk/wiki/index.php/Mitosis mitosis] process begins. Its function is to hold together the two sister [[Chromatid|chromatids]] <ref>Compendium for Medical Sciences (2008): pg 163, Banbury: Scion Publishing Limited,</ref>. | A centromere is present before the [http://bms.ncl.ac.uk/wiki/index.php/Mitosis mitosis] process begins. Its function is to hold together the two sister [[Chromatid|chromatids]] <ref>Compendium for Medical Sciences (2008): pg 163, Banbury: Scion Publishing Limited,</ref>. | ||
A [[ | A [[protein|protein]] known as the[[Kinetochore| kinetochore]] is built on the [[Centromere|centromere]]. The [[Kinetochore|kinetochore]] is important as it attaches the sister [[Chromatid|chromatids]] to the [[mitotic spindle|mitotic spindle]], allowing [[Chromosome|chromosome]] division <ref>Bruce Alberts, Molecular Biology of the Cell (2008): pg 1082-1083, Fifth Edition, New York: Garland Science.</ref>. | ||
[[Centromeres|Centromeres]] in higher eukaryotes usually consist of long repeated base sequences. In humans these repeated sequences are known as [[Alpha satellites]]. In eukaryotes such as ''[[S. cerevisiae|S. cerevisiae]]'' the centromere consists of a much smaller sequence (126 bp) <ref>Lodish et al.; Molecular Cell Biology; sixth edition 2008</ref> and is not a repeat. | [[Centromeres|Centromeres]] in higher eukaryotes usually consist of long repeated base sequences. In humans these repeated sequences are known as [[Alpha satellites]]. In eukaryotes such as ''[[S. cerevisiae|S. cerevisiae]]'' the centromere consists of a much smaller sequence (126 bp) <ref>Lodish et al.; Molecular Cell Biology; sixth edition 2008</ref> and is not a repeat. | ||
[[Centromeres|Centromeres]] do not necessarily have to be in the centre of the [[Chromosome|chromosome]], and [[Chromosome|chromosomes]] be classified according to position of the centromere. [[Metacentric chromosomes|Metacentric chromosomes]] have their centromere in the centre of the [[Chromosome|chromosome]], [[Submetacentric chromosomes|submetacentric]] have centromeres slightly off centre. Arcocentric [[Chromosome|chromosomes]] have long arms (q) and short arms (p) like submetacentric [[Chromosome|chromosomes]], however the centromere is slightly higher leaving longer long arms and shorter short arms. [[Telocentric chromosome|Telocentric chromosomes]] have their centromere at the top of the [[Chromosome|chromosome]]. | [[Centromeres|Centromeres]] do not necessarily have to be in the centre of the [[Chromosome|chromosome]], and [[Chromosome|chromosomes]] be classified according to position of the centromere. [[Metacentric chromosomes|Metacentric chromosomes]] have their centromere in the centre of the [[Chromosome|chromosome]], [[Submetacentric chromosomes|submetacentric]] have centromeres slightly off centre. Arcocentric [[Chromosome|chromosomes]] have long arms (q) and short arms (p) like submetacentric [[Chromosome|chromosomes]], however the centromere is slightly higher leaving longer long arms and shorter short arms. [[Telocentric chromosome|Telocentric chromosomes]] have their centromere at the top of the [[Chromosome|chromosome]]. | ||
A centromere is the part of a chromosome that joins two chromatids together, without them, [[cell|cells]] cannot divide properly and [[mitosis|mitosis]] could not occur, preventing cell replication.<br>Although part of the chromosome the centromere itself is a section of noncoding [[DNA|DNA]] and contains no genetic information. | |||
=== Function === | |||
Centromeres contain [[kinetochore|kinetochores]], these are the regions of the centromere that attach chromosomes to the spindles, seperating the chromosomes, during prophase of mitosis | |||
=== Position === | |||
They can vary on postion on the chromosome, being in the center (metacentric) or creating long and short arms if appearing slightly towards one end (submetacentric), <br>almost at the end (acrocentric) or joining the end of the chromatids (telocentric).<br>When creating karyotypes, the postion of the centromere is used to find matching pairs, as it can be very specific.<br> | |||
=== References === | === References === | ||
<references /> | <references /> | ||
Revision as of 09:53, 20 November 2011
A centromere is present before the mitosis process begins. Its function is to hold together the two sister chromatids [1].
A protein known as the kinetochore is built on the centromere. The kinetochore is important as it attaches the sister chromatids to the mitotic spindle, allowing chromosome division [2].
Centromeres in higher eukaryotes usually consist of long repeated base sequences. In humans these repeated sequences are known as Alpha satellites. In eukaryotes such as S. cerevisiae the centromere consists of a much smaller sequence (126 bp) [3] and is not a repeat.
Centromeres do not necessarily have to be in the centre of the chromosome, and chromosomes be classified according to position of the centromere. Metacentric chromosomes have their centromere in the centre of the chromosome, submetacentric have centromeres slightly off centre. Arcocentric chromosomes have long arms (q) and short arms (p) like submetacentric chromosomes, however the centromere is slightly higher leaving longer long arms and shorter short arms. Telocentric chromosomes have their centromere at the top of the chromosome.
A centromere is the part of a chromosome that joins two chromatids together, without them, cells cannot divide properly and mitosis could not occur, preventing cell replication.
Although part of the chromosome the centromere itself is a section of noncoding DNA and contains no genetic information.
Function
Centromeres contain kinetochores, these are the regions of the centromere that attach chromosomes to the spindles, seperating the chromosomes, during prophase of mitosis
Position
They can vary on postion on the chromosome, being in the center (metacentric) or creating long and short arms if appearing slightly towards one end (submetacentric),
almost at the end (acrocentric) or joining the end of the chromatids (telocentric).
When creating karyotypes, the postion of the centromere is used to find matching pairs, as it can be very specific.
References