Chromosome set
In the genetics of eukaryotes, the chromosome set describes the number of chromosomes in the nucleus of a cell .
If the chromosomes of a eukaryotic cell are examined more closely and compared with one another, chromosomes of the same size are often found that also contain homologous genes . If the cell nucleus has two such homologous chromosomes that correspond to one another , the cell has a double set of chromosomes (2 n ); this is known as diploid . In humans, like most vertebrates , this condition is present in most of the body cells , they have a double set of chromosomes. In humans this is a total of 46 chromosomes: two copies each of chromosome 1 , from chromosome 2 and so on to chromosome 22 (44 autosomes ) and two sex chromosomes (2 gonosomes ), namely two X chromosomes in females or one X and one Y -Chromosome in males.
Human germ cells, on the other hand, have a simple set of chromosomes (1 n ), they are haploid , since the number of chromosomes per cell was halved by the reduction division in meiosis . A simple human chromosome set consists of 23 chromosomes ( n = 23), namely one chromosome 1, one chromosome 2 and so on up to chromosome 22 and one sex chromosome, i.e. the X chromosome or the Y chromosome.
If a cell has a normal set ( s ) of chromosomes or an integer multiple thereof (2 n , 3 n , ...), it is euploid . If there is a different number of chromosomes, i.e. too many or too few chromosomes, this is called aneuploidy .
Names depending on the number of chromosome sets
- Haploidy , simple set of chromosomes
- Diploidy , double set of chromosomes
- Triploidy , triple set of chromosomes
- Tetraploidy , quadruple set of chromosomes
A multiple set of chromosomes over 2 n is also called polyploidy .
The number of chromosome sets can be used to classify organisms:
The composition of chromosome sets can be used to characterize cell states:
See also
- Degree of ploidy ,
- Non-diploid number of chromosome sets
- Karyotype , characteristics of the set of chromosomes
- Karyogram , representation of the chromosome set
swell
- Werner Buselmaier, Gholamali Tariverdian: Human Genetics . 4th edition. Springer Medizin Verlag, Heidelberg 2006, ISBN 978-3-540-32677-9 , p. 123 .