Cytogenetics

thumb|Different representations of chromosomes thumb|Main parts of a condensed chromosome thumb|212x212px|Condensed chromosome (purple rod) inside a bone marrow erythrokaryocyte undergoing mitosis

thumb|upright|A haploid set that consists of a single complete set of chromosomes (equal to the monoploid set), as shown in the picture above, must belong to a diploid species. If a haploid set consists of two sets, it must be of a tetraploid (four sets) species.

An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA.

A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by determining the chromosome complement of an individual, including the number of chromosomes and any abnormalities. thumb|Micrographic karyogram of human male using [[Giemsa staining]] thumb|Schematic karyogram demonstrating the basic knowledge needed to read a karyotype A karyogram or idiogram is a graphical depiction of a karyotype, wherein chromosomes

sex chromosome present in both sexes, of species in which the male is the heterogametic sex

right|thumb|A metaphase cell positive for the BCR/ABL rearrangement using FISH Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology (a subdivision of human anatomy), that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. Techniques used include karyotyping, analysis of G-banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH).

abnormal number or structure of chromosomes

phenomenon that results in unusual rearrangement of chromosomes

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human somatic cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell.

German biologist (1843–1905)

A trisomy is a type of polysomy in which there are three instances of a particular chromosome, instead of the normal two. A trisomy is a type of aneuploidy (an abnormal number of chromosomes).

genetic testing technique

thumb|Schematic karyotype|karyogram of a human, showing the normal [[diploid karyotype. It shows annotated bands and sub-bands as used for the nomenclature of chromosome abnormalities including partial monosomies. It shows 22 homologous chromosomes, both the female (XX) and male (XY) versions of the sex chromosome (bottom right), as well as the mitochondrial genome (to scale at bottom left).]] Monosomy is a form of aneuploidy with the presence of only one chromosome from a pair. Partial monosomy occurs when a portion of one chromosome in a pair is missing.

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presence in a cell of two paired chromosomes from the same parent, with no chromosome of that pair from the other parent

region of sexual chromosomes exhibiting an autosomal inheritance pattern

Two identical copies of a chromatids

Indian geneticist (1932-2008)

chromosome abnormality involving a change in the structure of the native chromosome

grass species

biological concept

Human disease

chromosomal rearrangement in pairs 13, 14, 15, 21, and 22

method to evaluate biological samples

thumb|Synapsis during meiosis. The circled area is the part where synapsis occurs, where the two chromatids meet before crossing over Synapsis or syzygy is the pairing of two chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis. When homologous chromosomes synapse, their ends are first attached to the nuclear envelope. These end-membrane complexes then migrate, assisted by the extranuclear cytoskeleton, until matching ends have been paired.

right|thumb|200px|Image of chicken chromosomes featuring the many microchromosomes (appearing as dots). The arrows indicate a stained gene locus on homologous macrochromosomes.

A tetrasomy is a form of aneuploidy with the presence of four copies, instead of the normal two, of a particular chromosome.