Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent. However, polyploidy is found in some organisms and is especially common in plants. In addition, polyploidy occurs in some tissues of animals that are otherwise diploid, such as human muscle tissues. This is known as endopolyploidy. Species whose cells do not have nuclei, that is, Prokaryotes, may be polyploid organisms, as seen in the large bacterium Epulopiscium fishelsoni . Hence ploidy is defined with respect to a cell. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Male bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis, the sporophyte generation is diploid and produces spores by meiosis.
Polyploidy refers to a numerical change in a whole set of chromosomes. Organisms in which a particular chromosome, or chromosome segment, is under- or overrepresented are said to be aneuploid (from the Greek words meaning “not“, “good“, and “fold“). Therefore, the distinction between aneuploidy and polyploidy is that aneuploidy refers to a numerical change in part of the chromosome set, whereas polyploidy refers to a numerical change in the whole set of chromosomes.
Polyploidy may occur due to abnormal cell division, either during mitosis, or commonly during metaphase I in meiosis.
Polyploidy occurs in some animals, such as goldfish, salmon, and salamanders, but is especially common among ferns and flowering plants (see Hibiscus rosa-sinensis), including both wild and cultivated species. Wheat, for example, after millennia of hybridization and modification by humans, has strains that are diploid (two sets of chromosomes), tetraploid (four sets of chromosomes) with the common name of durum or macaroni wheat, and hexaploid (six sets of chromosomes) with the common name of bread wheat. Many agriculturally important plants of the genus Brassica are also tetraploids.
Polyploidy can be induced in plants and cell cultures by some chemicals: the best known is colchicine, which can result in chromosome doubling, though its use may have other less obvious consequences as well. Oryzalin will also double the existing chromosome content.
#polyploid #eukaryotes #endopolyploidy #monoploid #chromosomes #Genetics #Tetraploid #hexaploid #colchicine
1 view
77
24
7 months ago 02:29:36 1
Ron Wyatt Discoveries [2022] Gomorrah, Red Sea Crossing, Mt Sinai, Noah’s Ark, Blood of Christ
10 months ago 00:06:47 1
Meiosis
11 months ago 00:29:56 1
Meiosis steps | what is the purpose of meiosis - Animated Lecture (Embryology)
1 year ago 01:11:19 1
Multiplex Immunofluorescence Profiling of Tumor Biopsies Using UltraPlex mxIF Technology
1 year ago 00:31:26 1
The Young Science of Ancient DNA
1 year ago 00:07:36 1
Probability calculations
1 year ago 00:04:59 1
Crossing-over and Gene mapping
1 year ago 00:13:25 1
Crossing Over, Gene Recombination
1 year ago 00:12:30 1
Cis and Trans | Coupling Repulsion | Gene recombination
1 year ago 00:06:40 1
Gene recombination | Dihybrid test cross
1 year ago 00:04:19 1
ZW sex-determination system
1 year ago 00:22:08 1
Gene recombination | Repulsion | Coupling
2 years ago 00:05:28 1
Chromosomal Crossover
2 years ago 00:07:15 1
Crossing Over | Linked Genes | Genetic Recombination
2 years ago 00:05:40 1
How Gene Mapping Works
2 years ago 00:04:36 1
How to calculate Phenotype and Genotype Frequencies
2 years ago 00:06:28 1
Incomplete dominance explained with examples
2 years ago 00:06:10 1
Crossing-over and chromosome mapping
2 years ago 00:13:32 1
Recombination and Estimating the Distance Between Genes
2 years ago 00:10:37 1
LINKAGE, CROSSING-OVER, & GENE MAPPING IN DROSOPHILA