Ploidy

ploidy

[′plȯid·ē] (genetics) Number of complete chromosome sets in a nucleus: haploid (N), diploid (2N), triploid (3N), tetraploid (4N), and so on.

Ploidy

the number that indicates how many times the set of chromosomes characteristic of the germ cells of a given species is replicated in the cell nucleus. The majority of organisms that reproduce sexually are diploid, that is, each of their somatic cells contains two sets of chromosomes (one for each of the haploid germ cells or gametes). In nature and under artificial conditions, ploidy may change in multiples higher that two (eupioidy); there may also be a loss or gain of individual chromosomes (aneu-ploidy).

Euploid increase of the number of chromosome sets (poly-ploidization) occurs if the chromosomes do not separate during cell division. It may also result from the merging of nuclei containing more than one set of chromosomes. There are two types of polyploidy: autopolyploidy, in which the number of homologous sets of chromosomes is increased, and allopolyploidy, which arises when there is a joining, as a result of hybridization, of the genomes of various species. Nonseparation of genomes can occur only in part of the cells of some tissues (somatic polyploidy, which is characteristic of many multicellular animals and plants). Polyploidization can lead to the formation of new plant species and thus serves as an important factor in their evolution (as well as of unicellular organisms). Its significance for species formation in multicellular animals is apparently limited to par-thenogenetic forms. Aneuploidy leads to serious disruptions of development, which often lead to death of the organism and, therefore, does not play a significant role in evolution. Aneuploid cells are common in malignant tumors.

Methods have been elaborated for artificially altering ploidy. They are used to obtain economically valuable forms of plants and for research purposes (for example, to study the action of genes).

ploidy

ploi·dy

(ploy'dē), The number of haploid sets in a cell. Gametes normally contain one; somatic cells two.
See also: polyploidy. [-ploid + -y, condition]

ploidy

(ploi′dē)n. A multiple of the basic number of chromosomes in a cell.

ploi·dy

(ploy'dē) The number of haploid sets in a cell. Gametes normally contain one; autosomal cells, two.
See also: polyploidy[ploid + -y, condition]

ploidy

The number of copies of the set of chromosomes in a cell. A normal diploid cell with two copies has a ploidy of two; a haploid cell with one copy, such as an ovum or a spermatozoon, has a ploidy of one.

ploidy

the number of chromosome sets making up the total genome of an organism.

Thus the ploidy of normal humans is two and is written 2n. See DIPLOID (1).

See ploidy

单词	ploidy
释义	ploidy ploi·dy P0377900 (ploi′dē)n. A multiple of the basic number of chromosomes in a cell. [From diploidy and haploidy.] ploi•dy (ˈplɔɪ di) n. the number of chromosome sets in the nucleus of a cell. [1935–40; see -ploid, -y³] Ploidy ploidy [′plȯid·ē] (genetics) Number of complete chromosome sets in a nucleus: haploid (N), diploid (2N), triploid (3N), tetraploid (4N), and so on. Ploidy the number that indicates how many times the set of chromosomes characteristic of the germ cells of a given species is replicated in the cell nucleus. The majority of organisms that reproduce sexually are diploid, that is, each of their somatic cells contains two sets of chromosomes (one for each of the haploid germ cells or gametes). In nature and under artificial conditions, ploidy may change in multiples higher that two (eupioidy); there may also be a loss or gain of individual chromosomes (aneu-ploidy). Euploid increase of the number of chromosome sets (poly-ploidization) occurs if the chromosomes do not separate during cell division. It may also result from the merging of nuclei containing more than one set of chromosomes. There are two types of polyploidy: autopolyploidy, in which the number of homologous sets of chromosomes is increased, and allopolyploidy, which arises when there is a joining, as a result of hybridization, of the genomes of various species. Nonseparation of genomes can occur only in part of the cells of some tissues (somatic polyploidy, which is characteristic of many multicellular animals and plants). Polyploidization can lead to the formation of new plant species and thus serves as an important factor in their evolution (as well as of unicellular organisms). Its significance for species formation in multicellular animals is apparently limited to par-thenogenetic forms. Aneuploidy leads to serious disruptions of development, which often lead to death of the organism and, therefore, does not play a significant role in evolution. Aneuploid cells are common in malignant tumors. Methods have been elaborated for artificially altering ploidy. They are used to obtain economically valuable forms of plants and for research purposes (for example, to study the action of genes). ploidy ploi·dy (ploy'dē), The number of haploid sets in a cell. Gametes normally contain one; somatic cells two. See also: polyploidy. [-ploid + -y, condition] ploidy (ploi′dē)n. A multiple of the basic number of chromosomes in a cell. ploi·dy (ploy'dē) The number of haploid sets in a cell. Gametes normally contain one; autosomal cells, two. See also: polyploidy[ploid + -y, condition] ploidy The number of copies of the set of chromosomes in a cell. A normal diploid cell with two copies has a ploidy of two; a haploid cell with one copy, such as an ovum or a spermatozoon, has a ploidy of one. ploidy the number of chromosome sets making up the total genome of an organism. Thus the ploidy of normal humans is two and is written 2n. See DIPLOID (1). See ploidy ThesaurusSeediploidy
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