A chromosome (from ancient Greek: χρωμόσωμα, chromosoma,
chroma means colour, soma means body) is a
DNA molecule with part or
all of the genetic material (genome) of an organism. Most eukaryotic
chromosomes include packaging proteins which, aided by chaperone
proteins, bind to and condense the
DNA molecule to prevent it from
becoming an unmanageable tangle.
Chromosomes are normally visible under a light microscope only when
the cell is undergoing the metaphase of cell division (where all
chromosomes are aligned in the center of the cell in their condensed
form). Before this happens, every chromosome is copied once (S
phase), and the copy is joined to the original by a centromere,
resulting either in an X-shaped structure (pictured to the right) if
the centromere is located in the middle of the chromosome or a two-arm
structure if the centromere is located near one of the ends. The
original chromosome and the copy are now called sister chromatids.
During metaphase the X-shape structure is called a metaphase
chromosome. In this highly condensed form chromosomes are easiest to
distinguish and study. In animal cells, chromosomes reach their
highest compaction level in anaphase during segregation.
Chromosomal recombination during meiosis and subsequent sexual
reproduction play a significant role in genetic diversity. If these
structures are manipulated incorrectly, through processes known as
chromosomal instability and translocation, the cell may undergo
mitotic catastrophe and die. Mutations in the cell can allow it to
inappropriately evade apoptosis and lead to the progression of cancer.
Some use the term chromosome in a wider sense, to refer to the
individualized portions of chromatin in cells, either visible or not
under light microscopy. Others use the concept in a narrower sense, to
refer to the individualized portions of chromatin during cell
division, visible under light microscopy due to high condensation.
2 History of discovery
3.1 Structure in sequences
Metaphase chromatin and division
5 Number in various organisms
5.1 In eukaryotes
5.2 In prokaryotes
6.1 Historical note
7.1 Sperm aneuploidy
8 See also
9 Notes and references
10 External links
The word chromosome (/ˈkroʊməˌsoʊm, -ˌzoʊm/) comes from
the Greek χρῶμα (chroma, "colour") and σῶμα (soma, "body"),
describing their strong staining by particular dyes. The term was
coined by von Waldeyer-Hartz, referring to the term chromatin,
which was introduced by Walther Flemming.
Emilio Battaglia (1917-2011) points out that over time many of
the most familiar caryological terms have become inadequate or
illogical or, in some cases, etymologically incorrect so that they
should be replaced by more adequate alternatives suggested by the
present scientific progress. The author has been particularly
disappointed by the illogicality of the present chromosomal
(chromatin-chromosome) terminology based on, or inferred by, two
Chromatin (Flemming 1880) and Chromosom (Waldeyer 1888), both
inappropriately ascribed to a basically non coloured state.
History of discovery
Walter Sutton (left) and
Theodor Boveri (right) independently
developed the chromosome theory of inheritance in 1902.
Schleiden, Virchow and Bütschli were among the first scientists
who recognized the structures now familiar as chromosomes.
In a series of experiments beginning in the mid-1880s, Theodor Boveri
gave the definitive demonstration that chromosomes are the vectors of
heredity. His two principles were the continuity of chromosomes and
the individuality of chromosomes.[further explanation
needed] It is the second of these principles that was so
Wilhelm Roux suggested that each chromosome
carries a different genetic load. Boveri was able to test and confirm
this hypothesis. Aided by the rediscovery at the start of the 1900s of
Gregor Mendel's earlier work, Boveri was able to point out the
connection between the rules of inheritance and the behaviour of the
chromosomes. Boveri influenced two generations of American
cytologists: Edmund Beecher Wilson, Nettie Stevens,
Walter Sutton and
Theophilus Painter were all influenced by Boveri (Wilson, Stevens, and
Painter actually worked with him).
In his famous textbook The Cell in Development and Heredity, Wilson
linked together the independent work of Boveri and Sutton (both around
1902) by naming the chromosome theory of inheritance the
Boveri–Sutton chromosome theory
Boveri–Sutton chromosome theory (the names are sometimes
Ernst Mayr remarks that the theory was hotly contested
by some famous geneticists: William Bateson, Wilhelm Johannsen,
Richard Goldschmidt and T.H. Morgan, all of a rather dogmatic turn of
mind. Eventually, complete proof came from chromosome maps in Morgan's
The number of human chromosomes was published in 1923 by Theophilus
Painter. By inspection through the microscope, he counted 24 pairs,
which would mean 48 chromosomes. His error was copied by others and it
was not until 1956 that the true number, 46, was determined by
Indonesia-born cytogeneticist Joe Hin Tjio.
The prokaryotes – bacteria and archaea – typically have
a single circular chromosome, but many variations exist. The
chromosomes of most bacteria, which some authors prefer to call
genophores, can range in size from only 130,000 base pairs in the
endosymbiotic bacteria Candidatus Hodgkinia cicadicola and
Candidatus Tremblaya princeps, to more than 14,000,000 base pairs
in the soil-dwelling bacterium Sorangium cellulosum. Spirochaetes
of the genus Borrelia are a notable exception to this arrangement,
with bacteria such as Borrelia burgdorferi, the cause of Lyme disease,
containing a single linear chromosome.
Structure in sequences
Prokaryotic chromosomes have less sequence-based structure than
Bacteria typically have a one-point (the origin of
replication) from which replication starts, whereas some archaea
contain multiple replication origins. The genes in prokaryotes are
often organized in operons, and do not usually contain introns, unlike
Prokaryotes do not possess nuclei. Instead, their
DNA is organized
into a structure called the nucleoid. The nucleoid is a
distinct structure and occupies a defined region of the bacterial
cell. This structure is, however, dynamic and is maintained and
remodeled by the actions of a range of histone-like proteins, which
associate with the bacterial chromosome. In archaea, the
chromosomes is even more organized, with the
DNA packaged within
structures similar to eukaryotic nucleosomes.
Certain bacteria also contain plasmids or other extrachromosomal DNA.
These are circular structures in the cytoplasm that contain cellular
DNA and play a role in horizontal gene transfer. In prokaryotes
(see nucleoids) and viruses, the
DNA is often densely packed and
organized; in the case of archaea, by homology to eukaryotic histones,
and in the case of bacteria, by histone-like proteins.
Bacterial chromosomes tend to be tethered to the plasma membrane of
the bacteria. In molecular biology application, this allows for its
isolation from plasmid
DNA by centrifugation of lysed bacteria and
pelleting of the membranes (and the attached DNA).
Prokaryotic chromosomes and plasmids are, like eukaryotic DNA,
generally supercoiled. The
DNA must first be released into its relaxed
state for access for transcription, regulation, and replication.
DNA in a eukaryotic cell.
Eukaryotic chromosome fine structure
Chromosomes in eukaryotes are composed of chromatin fiber. Chromatin
fiber is made of nucleosomes (histone octamers with part of a DNA
strand attached to and wrapped around it).
Chromatin fibers are
packaged by proteins into a condensed structure called chromatin.
Chromatin contains the vast majority of
DNA and a small amount
inherited maternally, can be found in the mitochondria.
present in most cells, with a few exceptions, for example, red blood
Chromatin allows the very long
DNA molecules to fit into the cell
nucleus. During cell division chromatin condenses further to form
microscopically visible chromosomes. The structure of chromosomes
varies through the cell cycle. During cellular division chromosomes
are replicated, divided, and passed successfully to their daughter
cells so as to ensure the genetic diversity and survival of their
progeny. Chromosomes may exist as either duplicated or unduplicated.
Unduplicated chromosomes are single double helixes, whereas duplicated
chromosomes contain two identical copies (called chromatids or sister
chromatids) joined by a centromere.
The major structures in
DNA compaction: DNA, the nucleosome, the
10 nm "beads-on-a-string" fibre, the 30 nm fibre and the
Eukaryotes (cells with nuclei such as those found in plants, fungi,
and animals) possess multiple large linear chromosomes contained in
the cell's nucleus. Each chromosome has one centromere, with one or
two arms projecting from the centromere, although, under most
circumstances, these arms are not visible as such. In addition, most
eukaryotes have a small circular mitochondrial genome, and some
eukaryotes may have additional small circular or linear cytoplasmic
In the nuclear chromosomes of eukaryotes, the uncondensed
in a semi-ordered structure, where it is wrapped around histones
(structural proteins), forming a composite material called chromatin.
During interphase (the period of the cell cycle where the cell is not
dividing), two types of chromatin can be distinguished:
Euchromatin, which consists of
DNA that is active, e.g., being
expressed as protein.
Heterochromatin, which consists of mostly inactive DNA. It seems to
serve structural purposes during the chromosomal stages.
Heterochromatin can be further distinguished into two types:
Constitutive heterochromatin, which is never expressed. It is located
around the centromere and usually contains repetitive sequences.
Facultative heterochromatin, which is sometimes expressed.
Each chromosome is made up of two chromatids(chromosomal arms) which
are joined to each other at a small constricted region called the
centromere.(Primary constriction). These sister chromatids are
conjoined twins the result of
The centromere helps the chromatids attach to the spindle fibres
during cell division, it is also concerned with the anaphase movement
of the chromosomes, by which the spindle fibers pull the chromatids to
the two opposite poles by their contraction during anaphase.
Besides the primary constriction, in certain chromosomes there is a
secondary constriction as well. Because a small portion is pinched off
from the chromosomal body; this portion is called a 'satellite' and
the chromosome is called an SAT chromosome.
The two chromatids are made up of very thin chromatin fibres which are
made up of 40%
DNA and 60% histone proteins
Each chromatin fibre consists of one
DNA helix coiled around eight
histone molecules like a loop; such a complex is called nucleosome and
resembles a bead on a string. These nucleosomes pack tighter, during
condensation required to get to metaphase.
The primary constriction cannot take up most stains, so during cell
division this region is a gap in staining.
Within the primary constriction there is a clear zone called
The centromere with the
DNA and histone proteins bound to them form a
disc shaped structure called kinetochore.
the chromonemata is a word that means a chromatid in the early stage
Metaphase chromatin and division
See also: mitosis and meiosis
Human chromosomes during metaphase
In the early stages of mitosis or meiosis (cell division), the
chromatin double helix become more and more condensed. They cease to
function as accessible genetic material (transcription stops) and
become a compact transportable form. This compact form makes the
individual chromosomes visible, and they form the classic four arm
structure, a pair of sister chromatids attached to each other at the
centromere. The shorter arms are called p arms (from the French petit,
small) and the longer arms are called q arms (q follows p in the Latin
alphabet; q-g "grande"; alternatively it is sometimes said q is short
for queue meaning tail in French). This is the only natural
context in which individual chromosomes are visible with an optical
Mitotic metaphase chromosomes are best described by a linearly
organized longitudinally compressed array of consecutive chromatin
During mitosis, microtubules grow from centrosomes located at opposite
ends of the cell and also attach to the centromere at specialized
structures called kinetochores, one of which is present on each sister
chromatid. A special
DNA base sequence in the region of the
kinetochores provides, along with special proteins, longer-lasting
attachment in this region. The microtubules then pull the chromatids
apart toward the centrosomes, so that each daughter cell inherits one
set of chromatids. Once the cells have divided, the chromatids are
DNA can again be transcribed. In spite of their
appearance, chromosomes are structurally highly condensed, which
enables these giant
DNA structures to be contained within a cell
Chromosomes in humans can be divided into two types: autosomes (body
chromosome(s)) and allosome (sex chromosome(s)). Certain genetic
traits are linked to a person's sex and are passed on through the sex
chromosomes. The autosomes contain the rest of the genetic hereditary
information. All act in the same way during cell division.
have 23 pairs of chromosomes (22 pairs of autosomes and one pair of
sex chromosomes), giving a total of 46 per cell. In addition to these,
human cells have many hundreds of copies of the mitochondrial genome.
Sequencing of the human genome has provided a great deal of
information about each of the chromosomes. Below is a table compiling
statistics for the chromosomes, based on the Sanger Institute's human
genome information in the Vertebrate
Genome Annotation (VEGA)
database. Number of genes is an estimate, as it is in part based
on gene predictions. Total chromosome length is an estimate as well,
based on the estimated size of unsequenced heterochromatin regions.
Estimated number of genes and base pairs (in mega base pairs) on each
Total base pairs
% of bases
Sequenced base pairs
X (sex chromosome)
Y (sex chromosome)
Number in various organisms
Main article: List of organisms by chromosome count
These tables give the total number of chromosomes (including sex
chromosomes) in a cell nucleus. For example, most eukaryotes are
diploid, like humans who have 22 different types of autosomes, each
present as two homologous pairs, and two sex chromosomes. This gives
46 chromosomes in total. Other organisms have more than two copies of
their chromosome types, such as bread wheat, which is hexaploid and
has six copies of seven different chromosome types – 42
chromosomes in total.
Chromosome numbers in some plants
Arabidopsis thaliana (diploid)
Einkorn wheat (diploid)
Maize (diploid or palaeotetraploid)
Durum wheat (tetraploid)
Bread wheat (hexaploid)
Cultivated tobacco (tetraploid)
Adder's tongue fern (polyploid)
Chromosome numbers (2n) in some animals
Common fruit fly
Pill millipede (Arthrosphaera fumosa)
Earthworm (Octodrilus complanatus)
Rabbit (Oryctolagus cuniculus)
Guppy (poecilia reticulata)
Chromosome numbers in other organisms
(Columba livia domestics)
2 sex chromosomes
Normal members of a particular eukaryotic species all have the same
number of nuclear chromosomes (see the table). Other eukaryotic
chromosomes, i.e., mitochondrial and plasmid-like small chromosomes,
are much more variable in number, and there may be thousands of copies
The 23 human chromosome territories during prometaphase in fibroblast
Asexually reproducing species have one set of chromosomes that are the
same in all body cells. However, asexual species can be either haploid
Sexually reproducing species have somatic cells (body cells), which
are diploid [2n] having two sets of chromosomes (23 pairs in humans
with one set of 23 chromosomes from each parent), one set from the
mother and one from the father. Gametes, reproductive cells, are
haploid [n]: They have one set of chromosomes. Gametes are produced by
meiosis of a diploid germ line cell. During meiosis, the matching
chromosomes of father and mother can exchange small parts of
themselves (crossover), and thus create new chromosomes that are not
inherited solely from either parent. When a male and a female gamete
merge (fertilization), a new diploid organism is formed.
Some animal and plant species are polyploid [Xn]: They have more than
two sets of homologous chromosomes. Plants important in agriculture
such as tobacco or wheat are often polyploid, compared to their
Wheat has a haploid number of seven chromosomes,
still seen in some cultivars as well as the wild progenitors. The
more-common pasta and bread wheat types are polyploid, having 28
(tetraploid) and 42 (hexaploid) chromosomes, compared to the 14
(diploid) chromosomes in the wild wheat.
Prokaryote species generally have one copy of each major chromosome,
but most cells can easily survive with multiple copies. For
example, Buchnera, a symbiont of aphids has multiple copies of its
chromosome, ranging from 10–400 copies per cell. However, in
some large bacteria, such as
Epulopiscium fishelsoni up to 100,000
copies of the chromosome can be present. Plasmids and plasmid-like
small chromosomes are, as in eukaryotes, highly variable in copy
number. The number of plasmids in the cell is almost entirely
determined by the rate of division of the plasmid – fast
division causes high copy number.
Main article: Karyotype
Karyogram of a human male
In general, the karyotype is the characteristic chromosome complement
of a eukaryote species. The preparation and study of karyotypes is
part of cytogenetics.
Although the replication and transcription of
DNA is highly
standardized in eukaryotes, the same cannot be said for their
karyotypes, which are often highly variable. There may be variation
between species in chromosome number and in detailed organization. In
some cases, there is significant variation within species. Often there
1. variation between the two sexes
2. variation between the germ-line and soma (between gametes and the
rest of the body)
3. variation between members of a population, due to balanced genetic
4. geographical variation between races
5. mosaics or otherwise abnormal individuals.
Also, variation in karyotype may occur during development from the
The technique of determining the karyotype is usually called
karyotyping. Cells can be locked part-way through division (in
metaphase) in vitro (in a reaction vial) with colchicine. These cells
are then stained, photographed, and arranged into a karyogram, with
the set of chromosomes arranged, autosomes in order of length, and sex
chromosomes (here X/Y) at the end.
Like many sexually reproducing species, humans have special gonosomes
(sex chromosomes, in contrast to autosomes). These are XX in females
and XY in males.
See also: Argument from authority § Use in science
Investigation into the human karyotype took many years to settle the
most basic question: How many chromosomes does a normal diploid human
cell contain? In 1912, Hans von Winiwarter reported 47 chromosomes in
spermatogonia and 48 in oogonia, concluding an XX/XO sex determination
mechanism. Painter in 1922 was not certain whether the diploid
number of man is 46 or 48, at first favouring 46. He revised his
opinion later from 46 to 48, and he correctly insisted on humans
having an XX/XY system.
New techniques were needed to definitively solve the problem:
Using cells in culture
Arresting mitosis in metaphase by a solution of colchicine
Pretreating cells in a hypotonic solution 0.075 M KCl, which swells
them and spreads the chromosomes
Squashing the preparation on the slide forcing the chromosomes into a
Cutting up a photomicrograph and arranging the result into an
It took until 1954 before the human diploid number was confirmed as
46. Considering the techniques of Winiwarter and Painter,
their results were quite remarkable. Chimpanzees, the closest
living relatives to modern humans, have 48 chromosomes as do the other
great apes: in humans two chromosomes fused to form chromosome 2.
In Down syndrome, there are three copies of chromosome 21
Chromosomal aberrations are disruptions in the normal chromosomal
content of a cell and are a major cause of genetic conditions in
humans, such as Down syndrome, although most aberrations have little
to no effect. Some chromosome abnormalities do not cause disease in
carriers, such as translocations, or chromosomal inversions, although
they may lead to a higher chance of bearing a child with a chromosome
disorder. Abnormal numbers of chromosomes or chromosome sets, called
aneuploidy, may be lethal or may give rise to genetic disorders.
Genetic counseling is offered for families that may carry a chromosome
The gain or loss of
DNA from chromosomes can lead to a variety of
Human examples include:
Cri du chat, which is caused by the deletion of part of the short arm
of chromosome 5. "Cri du chat" means "cry of the cat" in French; the
condition was so-named because affected babies make high-pitched cries
that sound like those of a cat. Affected individuals have wide-set
eyes, a small head and jaw, moderate to severe mental health problems,
and are very short.
Down syndrome, the most common trisomy, usually caused by an extra
copy of chromosome 21 (trisomy 21). Characteristics include decreased
muscle tone, stockier build, asymmetrical skull, slanting eyes and
mild to moderate developmental disability.
Edwards syndrome, or trisomy-18, the second most common trisomy.
Symptoms include motor retardation, developmental disability and
numerous congenital anomalies causing serious health problems. Ninety
percent of those affected die in infancy. They have characteristic
clenched hands and overlapping fingers.
Isodicentric 15, also called idic(15), partial tetrasomy 15q, or
inverted duplication 15 (inv dup 15).
Jacobsen syndrome, which is very rare. It is also called the terminal
11q deletion disorder. Those affected have normal intelligence or
mild developmental disability, with poor expressive language skills.
Most have a bleeding disorder called Paris-Trousseau syndrome.
Klinefelter syndrome (XXY). Men with
Klinefelter syndrome are usually
sterile and tend to be taller and have longer arms and legs than their
peers. Boys with the syndrome are often shy and quiet and have a
higher incidence of speech delay and dyslexia. Without testosterone
treatment, some may develop gynecomastia during puberty.
Patau Syndrome, also called D-Syndrome or trisomy-13. Symptoms are
somewhat similar to those of trisomy-18, without the characteristic
Small supernumerary marker chromosome. This means there is an extra,
abnormal chromosome. Features depend on the origin of the extra
Cat-eye syndrome and isodicentric chromosome 15
syndrome (or Idic15) are both caused by a supernumerary marker
chromosome, as is Pallister–Killian syndrome.
Triple-X syndrome (XXX). XXX girls tend to be tall and thin and have a
higher incidence of dyslexia.
Turner syndrome (X instead of XX or XY). In Turner syndrome, female
sexual characteristics are present but underdeveloped. Females with
Turner syndrome often have a short stature, low hairline, abnormal eye
features and bone development and a "caved-in" appearance to the
Wolf–Hirschhorn syndrome, which is caused by partial deletion of the
short arm of chromosome 4. It is characterized by growth retardation,
delayed motor skills development, "Greek Helmet" facial features, and
mild to profound mental health problems.
XYY syndrome. XYY boys are usually taller than their siblings. Like
XXY boys and XXX girls, they are more likely to have learning
Exposure of males to certain lifestyle, environmental and/or
occupational hazards may increase the risk of aneuploid
spermatozoa. In particular, risk of aneuploidy is increased by
tobacco smoking, and occupational exposure to benzene,
insecticides, and perfluorinated compounds. Increased
aneuploidy is often associated with increased
DNA damage in
For information about chromosomes in genetic algorithms, see
chromosome (genetic algorithm)
List of number of chromosomes of various organisms
Locus (explains gene location nomenclature)
Maternal influence on sex determination
XY sex-determination system
Notes and references
^ Hammond, Colin M.; Strømme, Caroline B.; Huang, Hongda; Patel,
Dinshaw J.; Groth, Anja (2017). "
Histone chaperone networks shaping
chromatin function". Nature Reviews Molecular Cell Biology. 18 (3):
141–158. doi:10.1038/nrm.2016.159. ISSN 1471-0072.
^ Wilson, John (2002). Molecular biology of the cell : a problems
approach. New York: Garland Science. ISBN 0-8153-3577-6.
^ Alberts, Bruce; Bray, Dennis; Hopkin, Karen; Johnson, Alexander;
Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter (2014).
Essential Cell Biology (Fourth ed.). New York, NY, USA: Garland
Science. pp. 621–626. ISBN 978-0-8153-4454-4.
^ a b c Schleyden, M. J. (1847). Microscopical researches into the
accordance in the structure and growth of animals and plants.
^ Wolfram, Antonin; Neumann, Heinz (2016). "
and decondensation during mitosis". Current Opinion in Cell Biology.
Elsevier Ltd. 40: 19. doi:10.1016/j.ceb.2016.01.013. Retrieved
^ Jones, Daniel (2003) , Peter Roach, James Hartmann and Jane
Setter, eds., English Pronouncing Dictionary, Cambridge: Cambridge
University Press, ISBN 3-12-539683-2 CS1 maint: Uses editors
^ Coxx, H. J. (1925). Biological Stains - A Handbook on the Nature and
Uses of the Dyes Employed in the Biological Laboratory. Commission on
Standardization of Biological Stains.
^ Waldeyer-Hartz (1888). "Über Karyokinese und ihre Beziehungen zu
den Befruchtungsvorgängen". Archiv für mikroskopische Anatomie und
Entwicklungsmechanik. 32: 27.
^ Garbari, Fabio; Bedini, Gianni; Peruzzi, Lorenzo (2012). "Chromosome
numbers of the Italian flora. From the Caryologia foundation to
present". Caryologia - International Journal of Cytology,
Cytosystematics and Cytogenetics. Oxfordshire, England: Taylor &
Francis. 65 (1): 65–66. doi:10.1080/00087114.2012.678090. Retrieved
^ Peruzzi, L.; Garbari, F.; Bedini, G. (2012). "New trends in plant
cytogenetics and cytoembryology: Dedicated to the memory of Emilio
Battaglia". Plant Biosystems - an International Journal Dealing. Pisa,
Italy: Taylor & Francis. 146 (3): 674–675.
doi:10.1080/11263504.2012.712553 (inactive 2018-03-26). Retrieved
^ Battaglia, Emilio (2009). "Caryoneme alternative to chromosome and a
new caryological nomenclature" (PDF). Caryologia - International
Journal of Cytology, Cytosystematics. Florence: Mozzon S.r.l. 62 (4):
1–80. Retrieved 2017-11-06.
^ Fokin S.I. (2013). "Otto Bütschli (1848–1920) Where we will
genuflect?" (PDF). Protistology. 8 (1): 22–35.
^ Carlson, Elof A. (2004). Mendel's Legacy: The Origin of Classical
Genetics (PDF). Cold Spring Harbor, NY: Cold Spring Harbor Laboratory
Press. p. 88. ISBN 978-087969675-7.
^ Wilson, E.B. (1925). The Cell in Development and Heredity, Ed. 3.
Macmillan, New York. p. 923.
^ Mayr, E. (1982). The growth of biological thought. Harvard. p. 749.
^ Matthews, Robert. "The bizarre case of the chromosome that never
was" (PDF). Archived from the original (PDF) on 15 December 2013.
Retrieved 13 July 2013. [self-published source?]
^ Thanbichler M; Shapiro L (2006). "
Chromosome organization and
segregation in bacteria". J. Struct. Biol. 156 (2): 292–303.
doi:10.1016/j.jsb.2006.05.007. PMID 16860572.
^ Van Leuven, JT; Meister, RC; Simon, C; McCutcheon, JP (11 September
2014). "Sympatric speciation in a bacterial endosymbiont results in
two genomes with the functionality of one". Cell. 158 (6): 1270–80.
doi:10.1016/j.cell.2014.07.047. PMID 25175626.
^ McCutcheon, JP; von Dohlen, CD (23 August 2011). "An interdependent
metabolic patchwork in the nested symbiosis of mealybugs". Current
Biology. 21 (16): 1366–72. doi:10.1016/j.cub.2011.06.051.
PMC 3169327 . PMID 21835622.
^ Han, K; Li, ZF; Peng, R; Zhu, LP; Zhou, T; Wang, LG; Li, SG; Zhang,
XB; Hu, W; Wu, ZH; Qin, N; Li, YZ (2013). "Extraordinary expansion of
Sorangium cellulosum genome from an alkaline milieu". Scientific
Reports. 3: 2101. doi:10.1038/srep02101. PMC 3696898 .
^ Hinnebusch J; Tilly K (1993). "Linear plasmids and chromosomes in
bacteria". Mol Microbiol. 10 (5): 917–22.
doi:10.1111/j.1365-2958.1993.tb00963.x. PMID 7934868.
^ Kelman LM; Kelman Z (2004). "Multiple origins of replication in
archaea". Trends Microbiol. 12 (9): 399–401.
doi:10.1016/j.tim.2004.07.001. PMID 15337158.
^ Thanbichler M; Wang SC; Shapiro L (2005). "The bacterial nucleoid: a
highly organized and dynamic structure". J. Cell. Biochem. 96 (3):
506–21. doi:10.1002/jcb.20519. PMID 15988757.
^ Le TB, Imakaev MV, Mirny LA, Laub MT (2013). "High-resolution
mapping of the spatial organization of a bacterial chromosome".
Science. 342 (6159): 731–4. doi:10.1126/science.1242059.
PMC 3927313 . PMID 24158908.
^ Sandman K; Pereira SL; Reeve JN (1998). "Diversity of prokaryotic
chromosomal proteins and the origin of the nucleosome". Cell. Mol.
Life Sci. 54 (12): 1350–64. doi:10.1007/s000180050259.
^ Sandman K; Reeve JN (2000). "Structure and functional relationships
of archaeal and eukaryal histones and nucleosomes". Arch. Microbiol.
173 (3): 165–9. doi:10.1007/s002039900122. PMID 10763747.
^ Pereira SL; Grayling RA; Lurz R; Reeve JN (1997). "Archaeal
nucleosomes". Proc. Natl. Acad. Sci. U.S.A. 94 (23): 12633–7.
PMC 25063 . PMID 9356501.
^ Johnson, J.; Chiu, W. (1 April 2000). "Structures of virus and
virus-like particles". Current Opinion in Structural Biology. 10 (2):
Chromosome Mapping: Idiograms" Nature Education - August 13, 2013
^ Naumova N, Imakaev M, Fudenberg G, Zhan Y, Lajoie BR, Mirny LA,
Dekker J (2013). "Organization of the mitotic chromosome". Science.
342 (6161): 948–53. doi:10.1126/science.1236083.
PMC 4040465 . PMID 24200812.
^ Vega.sanger.ad.uk, all data in this table was derived from this
database, November 11, 2008.
Ensembl genome browser 71: Homo sapiens –
Chromosome summary –
Chromosome 1: 1–1,000,000". apr2013.archive.ensembl.org. Retrieved
^ Sequenced percentages are based on fraction of euchromatin portion,
Genome Project goals called for determination of only the
euchromatic portion of the genome. Telomeres, centromeres, and other
heterochromatic regions have been left undetermined, as have a small
number of unclonable gaps. See
https://www.ncbi.nlm.nih.gov/genome/seq/ for more information on the
^ Armstrong SJ; Jones GH (January 2003). "Meiotic cytology and
chromosome behaviour in wild-type Arabidopsis thaliana". J. Exp. Bot.
54 (380): 1–10. doi:10.1093/jxb/54.380.1. PMID 12456750.
^ Gill BS; Kimber G (April 1974). "The Giemsa C-Banded
Rye". Proc. Natl. Acad. Sci. U.S.A. 71 (4): 1247–9.
PMC 388202 . PMID 4133848.
^ a b c Dubcovsky J; Luo MC; Zhong GY; et al. (1996). "Genetic Map of
Diploid Wheat, Triticum Monococcum L., and Its Comparison with Maps of
Hordeum Vulgare L". Genetics. 143 (2): 983–99. PMC 1207354 .
^ Kato A; Lamb JC; Birchler JA (September 2004). "
DNA sequences as probes for somatic chromosome
identification in maize". Proc. Natl. Acad. Sci. U.S.A. 101 (37):
13554–9. Bibcode:2004PNAS..10113554K. doi:10.1073/pnas.0403659101.
PMC 518793 . PMID 15342909.
^ Kenton A; Parokonny AS; Gleba YY; Bennett MD (August 1993).
"Characterization of the Nicotiana tabacum L. genome by molecular
cytogenetics". Mol. Gen. Genet. 240 (2): 159–69.
doi:10.1007/BF00277053. PMID 8355650.
^ Leitch IJ; Soltis DE; Soltis PS; Bennett MD (2005). "Evolution of
DNA amounts across land plants (embryophyta)". Ann. Bot. 95 (1):
207–17. doi:10.1093/aob/mci014. PMID 15596468.
^ Ambarish, C.N. Sridhar, K.R. (2014). "Cytological and karyological
observations of two endemic pill-millipedes Arthrosphaera (Pocock,
1895) (Diplopoda: Sphaerotheriida) of the Western Ghats of India".
Caryologia. 66 (1). doi:10.1080/00087114 (inactive
2018-03-26). CS1 maint: Multiple names: authors list (link)
^ Vitturi R; Colomba MS; Pirrone AM; Mandrioli M (2002). "rDNA
(18S-28S and 5S) colocalization and linkage between ribosomal genes
and (TTAGGG)(n) telomeric sequence in the earthworm, Octodrilus
complanatus (Annelida: Oligochaeta: Lumbricidae), revealed by single-
and double-color FISH". J. Hered. 93 (4): 279–82.
doi:10.1093/jhered/93.4.279. PMID 12407215.
^ Nie W; Wang J; O'Brien PC; et al. (2002). "The genome phylogeny of
domestic cat, red panda and five mustelid species revealed by
comparative chromosome painting and G-banding".
Chromosome Res. 10
(3): 209–22. doi:10.1023/A:1015292005631. PMID 12067210.
^ a b Romanenko, Svetlana A.; Perelman, Polina L.; Serdukova, Natalya
A.; Trifonov, Vladimir A.; Biltueva, Larisa S.; Wang, Jinhuan; Li,
Tangliang; Nie, Wenhui; O'Brien, Patricia C.M.; Volobouev, Vitaly T.;
Stanyon, Roscoe; Ferguson-Smith, Malcolm A.; Yang, Fengtang;
Graphodatsky, Alexander S. (2006). "Reciprocal chromosome painting
between three laboratory rodent species". Mammalian Genome. 17 (12):
1183–92. doi:10.1007/s00335-006-0081-z. PMID 17143584.
^ a b Painter, TS (1928). "A Comparison of the Chromosomes of the Rat
and Mouse with Reference to the Question of
Chromosome Homology in
Mammals". Genetics. 13 (2): 180–9. PMC 1200977 .
^ Hayes, H.; Rogel-Gaillard, C.; Zijlstra, C.; De Haan, N.A.; Urien,
C.; Bourgeaux, N.; Bertaud, M.; Bosma, A.A. (2002). "Establishment of
an R-banded rabbit karyotype nomenclature by FISH localization of 23
chromosome-specific genes on both G- and R-banded chromosomes".
Genome Research. 98 (2–3): 199–205.
doi:10.1159/000069807. PMID 12698004.
^ "The Genetics of the Popular Aquarium Pet -
Guppy Fish". Retrieved
^ a b De Grouchy J (1987). "
Chromosome phylogenies of man, great apes,
and Old World monkeys". Genetica. 73 (1–2): 37–52.
doi:10.1007/bf00057436. PMID 3333352.
^ T.J. Robinson; F. Yang; W.R. Harrison (2002). "
refines the history of genome evolution in hares and rabbits (order
Lagomorpha)". Cytogenetic and
Genome Research. 96 (1–4): 223–227.
doi:10.1159/000063034. PMID 12438803.
^ Chapman, Joseph A; Flux, John E. C (1990), "section 4.W4", Rabbits,
Hares and Pikas. Status Survey and Conservation Action Plan,
pp. 61–94, ISBN 9782831700199
^ Vitturi R; Libertini A; Sineo L; et al. (2005). "
Cytogenetics of the
land snails Cantareus aspersus and C. mazzullii (Mollusca: Gastropoda:
Pulmonata)". Micron. 36 (4): 351–7.
doi:10.1016/j.micron.2004.12.010. PMID 15857774.
^ Yasukochi Y; Ashakumary LA; Baba K; Yoshido A; Sahara K (2006). "A
Second-Generation Integrated Map of the Silkworm Reveals
Gene Order Between Lepidopteran Insects". Genetics. 173 (3):
1319–28. doi:10.1534/genetics.106.055541. PMC 1526672 .
^ Houck, M.L.; Kumamoto, A.T.; Gallagher, D.S.; Benirschke, K. (2001).
"Comparative cytogenetics of the African elephant (Loxodonta africana)
and Asiatic elephant (Elephas maximus)". Cytogenetic and Genome
Research. 93 (3–4): 249–52. doi:10.1159/000056992.
^ Umeko Semba; Yasuko Umeda; Yoko Shibuya; Hiroaki Okabe; Sumio Tanase
& Tetsuro Yamamoto (2004). "Primary structures of guinea pig high-
and low-molecular-weight kininogens". International
Immunopharmacology. 4 (10–11): 1391–1400.
doi:10.1016/j.intimp.2004.06.003. PMID 15313436.
^ Wayne RK; Ostrander EA (1999). "Origin, genetic diversity, and
genome structure of the domestic dog". BioEssays. 21 (3): 247–57.
^ Ciudad J; Cid E; Velasco A; Lara JM; Aijón J; Orfao A (2002). "Flow
cytometry measurement of the
DNA contents of G0/G1 diploid cells from
three different teleost fish species". Cytometry. 48 (1): 20–5.
doi:10.1002/cyto.10100. PMID 12116377.
^ Burt DW (2002). "Origin and evolution of avian microchromosomes".
Genome Res. 96 (1–4): 97–112. doi:10.1159/000063018.
^ Itoh, Masahiro; Ikeuchi, Tatsuro; Shimba, Hachiro; Mori, Michiko;
Sasaki, Motomichi; Makino, Sajiro (1969). "A Comparative Karyotype
Study in Fourteen
Species of Birds". The Japanese journal of genetics.
44 (3): 163–170. doi:10.1266/jjg.44.163.
^ Smith J; Burt DW (1998). "Parameters of the chicken genome (Gallus
gallus)". Anim. Genet. 29 (4): 290–4.
doi:10.1046/j.1365-2052.1998.00334.x. PMID 9745667.
^ Sakamura, Tetsu (1918). "Kurze Mitteilung über die
Chromosomenzahlen und die Verwandtschaftsverhältnisse der
Triticum-Arten". Shokubutsugaku Zasshi. 32 (379): 150–3.
^ Charlebois R.L. (ed) 1999. Organization of the prokaryote genome.
ASM Press, Washington DC.
^ Komaki K; Ishikawa H (March 2000). "Genomic copy number of
intracellular bacterial symbionts of aphids varies in response to
developmental stage and morph of their host". Insect Biochem. Mol.
Biol. 30 (3): 253–8. doi:10.1016/S0965-1748(99)00125-3.
^ Mendell JE; Clements KD; Choat JH; Angert ER (May 2008). "Extreme
polyploidy in a large bacterium". Proc. Natl. Acad. Sci. U.S.A. 105
(18): 6730–4. Bibcode:2008PNAS..105.6730M.
doi:10.1073/pnas.0707522105. PMC 2373351 .
^ White, M. J. D. (1973). The chromosomes (6th ed.). London: Chapman
and Hall, distributed by Halsted Press, New York. p. 28.
^ von Winiwarter H (1912). "Études sur la spermatogenèse humaine".
Archives de Biologie. 27 (93): 147–9.
^ Painter TS (1922). "The spermatogenesis of man". Anat. Res. 23:
^ Painter, Theophilus S. (April 1923). "Studies in mammalian
spermatogenesis. II. The spermatogenesis of man". Journal of
Experimental Zoology. 37 (3): 291–336.
^ Tjio JH; Levan A (1956). "The chromosome number of man". Hereditas.
42 (1–2): 1–6. doi:10.1111/j.1601-5223.1956.tb03010.x.
^ Ford C.E; Hamerton J.L (1956). "The Chromosomes of Man". Nature. 178
(4541): 1020–1023. Bibcode:1956Natur.178.1020F.
doi:10.1038/1781020a0. PMID 13378517.
^ Hsu T.C.
Human and mammalian cytogenetics: a historical perspective.
Springer-Verlag, N.Y. p10: "It's amazing that he [Painter] even came
^ Santaguida, Stefano; Amon, Angelika (2015-08-01). "Short- and
long-term effects of chromosome mis-segregation and aneuploidy".
Nature Reviews Molecular Cell Biology. 16 (8): 473–485.
doi:10.1038/nrm4025. ISSN 1471-0080. PMID 26204159.
^ Miller, Kenneth R. (2000). "Chapter 9-3". Biology (5th ed.). Upper
Saddle River, New Jersey: Prentice Hall. pp. 194–5.
^ "What is Trisomy 18?". Trisomy 18 Foundation. Retrieved 4 February
Chromosome 11 Network[not in citation given]
^ Templado C, Uroz L, Estop A (2013). "New insights on the origin and
relevance of aneuploidy in human spermatozoa". Mol. Hum. Reprod. 19
(10): 634–43. doi:10.1093/molehr/gat039. PMID 23720770.
^ Shi Q, Ko E, Barclay L, Hoang T, Rademaker A, Martin R (2001).
"Cigarette smoking and aneuploidy in human sperm". Mol. Reprod. Dev.
59 (4): 417–21. doi:10.1002/mrd.1048. PMID 11468778.
^ Rubes J, Lowe X, Moore D, Perreault S, Slott V, Evenson D, Selevan
SG, Wyrobek AJ (1998). "Smoking cigarettes is associated with
increased sperm disomy in teenage men". Fertil. Steril. 70 (4):
715–23. doi:10.1016/S0015-0282(98)00261-1. PMID 9797104.
^ Xing C, Marchetti F, Li G, Weldon RH, Kurtovich E, Young S, Schmid
TE, Zhang L, Rappaport S, Waidyanatha S, Wyrobek AJ, Eskenazi B
(2010). "Benzene exposure near the U.S. permissible limit is
associated with sperm aneuploidy". Environ. Health Perspect. 118 (6):
833–9. doi:10.1289/ehp.0901531. PMC 2898861 .
^ Xia Y, Bian Q, Xu L, Cheng S, Song L, Liu J, Wu W, Wang S, Wang X
(2004). "Genotoxic effects on human spermatozoa among pesticide
factory workers exposed to fenvalerate". Toxicology. 203 (1–3):
49–60. doi:10.1016/j.tox.2004.05.018. PMID 15363581.
^ Xia Y, Cheng S, Bian Q, Xu L, Collins MD, Chang HC, Song L, Liu J,
Wang S, Wang X (2005). "Genotoxic effects on spermatozoa of
carbaryl-exposed workers". Toxicol. Sci. 85 (1): 615–23.
doi:10.1093/toxsci/kfi066. PMID 15615886.
^ Governini L, Guerranti C, De Leo V, Boschi L, Luddi A, Gori M,
Orvieto R, Piomboni P (2015). "Chromosomal aneuploidies and DNA
fragmentation of human spermatozoa from patients exposed to
perfluorinated compounds". Andrologia. 47 (9): 1012–9.
doi:10.1111/and.12371. PMID 25382683.
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