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7) The diploid zygote which has just been fertilized by the union of haploid egg and sperm during sex. 8) Cells of the diploid structure quickly undergo meiosis to produce spores containing the meiotically halved number of chromosomes, restoring haploidy. These spores express either the mother's dominant gene or the father's recessive gene and ...
For example, consider a diploid organism and two bi-allelic loci (such as SNPs) on the same chromosome. Assume the first locus has alleles A or T and the second locus G or C . Both loci, then, have three possible genotypes : ( AA , AT , and TT ) and ( GG , GC , and CC ), respectively.
A similar relationship exists between three diploid species of Tragopogon (T. dubius, T. pratensis, and T. porrifolius) and two allotetraploid species (T. mirus and T. miscellus). [42] Complex patterns of allopolyploid evolution have also been observed in animals, as in the frog genus Xenopus .
In haploids produced from anther culture, it is observed that some plants are aneuploids and some are mixed haploid-diploid types. Another disadvantage associated with the double haploidy is the cost involved in establishing tissue culture and growth facilities. The over-usage of doubled haploidy may reduce genetic variation in breeding germplasm.
Diploid males would be infertile, as their cells would not undergo meiosis to form sperm. Therefore, the sperm would be diploid, which means that their offspring would be triploid . Since hymenopteran mother and sons share the same genes, they may be especially sensitive to inbreeding : Inbreeding reduces the number of different sex alleles ...
Diploid organisms form haploids by dividing, without replicating their DNA, to create daughter cells that randomly inherit one of each pair of chromosomes. Most animals and many plants are diploid for most of their lifespan, with the haploid form reduced to single cell gametes such as sperm or eggs .
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Alternation between a multicellular diploid and a multicellular haploid generation is never encountered in animals. [33] In some animals, there is an alternation between parthenogenic and sexually reproductive phases , for instance in salps and doliolids (class Thaliacea). Both phases are diploid.