Does anyone know what tetraploidy is?

Question

Thanks. Can anyone find any pictures of this disorder?

Answer 1

having or being a chromosome number four times the monoploid number

Answer 2

Definitions of Tetraploidy on the Web:

four copies of every chromosome in a cell, for a total of 92 chromosomes, instead of the typical number, 46 chromosomes.
www.medgen.ubc.ca/wrobinson/mosaic/glossary.htm

The presence in a cell of four haploid sets (23) of parental chromosomes, giving a total chromosome count of 92.
www.agsa-geneticsupport.org.au/glossary.html

Polyploid (in Greek: πολλαπλόν - multiple) cells or organisms contain more than two copies (ploidy) of their chromosomes. The polyploid types are termed triploid (3x), tetraploid (4x), pentaploid (5x), hexaploid (6x) and so on. Where an organism is normally diploid, a monoploid (1x) may arise as a spontaneous aberration; monoploidy may also occur as a normal stage in an organism's life cycle.
en.wikipedia.org/wiki/Tetraploidy

Answer 3

Dictionary.com says: 1. having a chromosome number that is four times the basic or haploid number.

Answer 4

A tetraploid organism's cells have four of every kind of chromosome. Tetra- means four.

People are diploid. Di- = 2. Your cells have two of every kind of chromosome.

Some plants are triploid. tri - = three. Their cells have three of each kind of chromosome.

Answer 5

Polyploidy is the condition of some biological cells and organisms of containing more than two homologous sets of chromosomes. Polyploid types are termed according to the number of chromosome sets in the nucleus: triploid (three sets; 3n), tetraploid (four sets; 4n), pentaploid (five sets; 5n), hexaploid (six sets; 6n) and so on.

A haploid (n) only has one set of chromosomes. Haploidy may also occur as a normal stage in an organism's life cycle as in ferns and fungi. In some instances not all the chromosomes are duplicated and the condition is called aneuploidy. Where an organism is normally diploid, some spontaneous aberrations may occur which are usually caused by a hampered cell division.




Examples
Polyploidy occurs in some animals, such as goldfish, salmon, and salamanders, but is especially common among ferns and flowering plants, 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; their relationship is described by the Triangle of U.


Speciation via polyploidy: A diploid cell undergoes failed meiosis, producing diploid gametes, which self-fertilize to produce a tetraploid zygote.Examples in animals are more common in the ‘lower’ forms such as flatworms, leeches, and brine shrimp. Polyploid animals are often sterile, so they often reproduce by parthenogenesis. Polyploid salamanders and lizards are also quite common and parthenogenetic. While mammalian liver cells are polyploid, rare instances of polyploid mammals are known, but most often result in prenatal death.

The only known exception to this rule is an octodontid rodent of Argentina's harsh desert regions, known as the Red Viscacha-Rat (Tympanoctomys barrerae), discovered by Milton Gallardo Narcisi, member of Universidad Austral de Chile. This rodent is not a rat, but kin to guinea pigs and chinchillas. Its "new" diploid [2n] number is 102 and so its cells are roughly twice normal size. Its closest living relation is Octomys mimax, the Andean Viscacha-Rat of the same family, whose 2n=56. It is surmised that an Octomys-like ancestor produced tetraploid (i.e., 4n=112) offspring that were, by virtue of their doubled chromosomes, reproductively isolated from their parents; but that these likely survived the ordinarily catastrophic effects of polyploidy in mammals by shedding (via translocation or some similar mechanism) the "extra" set of sex chromosomes gained at this doubling.

Polyploidy can be induced in cell culture 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.

In plant breeding, the induction of polyploids is a common technique to overcome the sterility of a hybrid species. Triticale is the hybrid of wheat (Triticum turgidum) and rye (Secale cereale). It combines sought-after characteristics of the parents, but the initial hybrids are sterile. After polyploidization, the hybrid becomes fertile and can thus be further propagated to become triticale.

Salsify or "goatsbeard" is another example of polyploidy resulting in new species.


[edit] Polyploidy in humans
Polyploidy occurs in humans in the form of triploidy (69,XXX ) and tetraploidy (92,XXXX). Triploidy occurs in about 2-3% of all human pregnancies and ~15% of miscarriages. The vast majority of triploid conceptions end as miscarriage and those that do survive to term typically die shortly after birth. In some cases survival past birth may occur longer if there is mixoploidy with both a diploid and a triploid cell population present.

Triploidy may be the result of either digyny (the extra haploid set is from the mother) or diandry (the extra haploid set is from the father). Diandry is almost always caused by the fertilization of an egg by two sperm (dispermy). Digyny is most commonly caused by either failure of one meiotic division during oogenesis leading to a diploid oocyte or failure to extrude one polar body from the oocyte. Diandry appears to predominate among early miscarriages while digyny predominates among triploidy that survives into the fetal period. However, among early miscarriages, digyny is also more common in those cases <8.5 weeks gestational age or those in which an embryo is present. There are also two distinct phenotypes in triploid placentas and fetuses that are dependent on the origin of the extra haploid set. In digyny there is typically an asymmetric poorly grown fetus, with marked adrenal hypoplasia and a very small placenta. In diandry, the fetus (when present) is typically normally grown or symmetrically growth restricted, with normal adrenal glands and an abnormally large cystic placenta that is called a partial hydatidiform mole. These parent-of-origin effects reflect the effects of genomic imprinting.

Complete tetraploidy is more rarely diagnosed than triploidy, but is observed in 1-2% of early miscarriages. However, some tetraploid cells are not uncommonly found in chromosome analysis at prenatal diagnosis and these are generally considered ‘harmless’. It is not clear whether these tetraploid cells simply tend to arise during in vitro cell culture or whether they are also present in placental cells in vivo. There are, at any rate, very few clinical reports of fetuses/infants diagnosed with tetraploidy mosaicism.

Mixoploidy is quite commonly observed in human preimplantation embryos and includes haploid/diploid as well as diploid/tetraploid mixed cell populations. It is unknown whether these embryos fail to implant and are therefore rarely detected in ongoing pregnancies or if there is simply a selective process favoring the diploid cells.


[edit] Polyploid crops
Polyploid plants in general are more robust and sturdy than diploids. In the breeding of crops, those plants that are stronger and tougher are selected. Thus many crops have unintentionally been bred to a higher level of ploidy:

Triploid crops: banana, apple, ginger
Tetraploid crops: durum or macaroni wheat, maize, cotton, potato, cabbage, leek, tobacco, peanut, kinnow, Pelargonium
Hexaploid crops: chrysanthemum, bread wheat, triticale, oat
Octaploid crops: strawberry, dahlia, pansies, sugar cane
Some crops are found in a variety of ploidy. Apples, tulips and lilies are commonly found as both diploid and as triploid. Daylilies (Hemerocallis) cultivars are available as either diploid or tetraploid. Kinnows can be tetraploid, diploid, or triploid.

Answer 6

Having four feet...............................