The monocentric chromosome is a chromosome that has only one
centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers a ...
in a
chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
and forms a narrow constriction.
Monocentric centromeres are the most common structure on highly repetitive DNA in plants and animals.
Structure
Monocentric chromosomes as compared to
holocentric chromosomes Holocentric chromosomes are chromosomes that possess multiple kinetochores along their length rather than the single centromere typical of other chromosomes. They were first described in cytogenetic experiments in 1935. Since this first observation, ...
where the entire length of the chromosome acts as the centromere. In monocentric chromosomes there is one primary constriction and the centromere its CenH3 loci at this location.
Holocentric chromosomes are found throughout the plant and animal kingdoms such as the nematode ''
Caenorhabditis elegans
''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (ro ...
''.
Holocentric chromosomes do have an evolutionary advantage by preventing the loss of chromosome after a DNA double-strand break.
The centromere is the point of attachment for the
mitotic apparatus
In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a ...
Chromosomal aberrations
Deletions, duplications and translocations can produce a
polycentric chromosome In genetics, a polycentric chromosome is any chromosome featuring multiple centromeres. Polycentric chromosomes are produced by chromosomal aberrations such as deletion, duplication, or translocation. Polycentric chromosomes usually result in the d ...
. This is troublesome for cells that divide often since at the time of
anaphase
Anaphase () is the stage of mitosis after the process of metaphase, when replicated chromosomes are split and the newly-copied chromosomes (daughter chromatids) are moved to opposite poles of the cell. Chromosomes also reach their overall maxim ...
the polycentric chromosome does not move to opposite poles of spindle fiber and the cell dies.
See also
*
Metacentric
Metacentric may refer to:
* Metacentric height
The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger ...
*
Submetacentric
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers ...
*
Acrocentric
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers ...
*
Telocentric
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers ...
References
{{Chromo
Chromosomes
Classical genetics
DNA replication