Ploidy haploid

MEIOSIS The process by which a eukaryotic cell nucleus (in which the DNA has been replicated only once) undergoes two coordinated divisions that yield four cells, each having ploidy half that of the original cell in higher animals, meiosis provides for the production of haploid sperms or eggs from diploid spermatocytes or oocytes. (See also MITOSIS)... 

PLOIDY Refers to the number of sets of chromosomes in a cell or organism—1 set in monoploids (haploids), 2 in diploids, 3 in triploids, 4 in tetraploids, etc. 

The existence of different morphotypes, two ploidy levels related to phase changes, and the ability of both haploid and diploid stages to divide mitotically (Kornmann 1955 Rousseau et al. 1994 Vaulot et al. 1994), support the existence of a haploid-diploid life cycle in P. globosa. In such life cycles, both haploid and diploid stages are related by sexual processes, meiosis and syngamy, and both are capable of mitotic division (Fig. 3 ... 

Still parahomologous events are valuable for other purposes. Thus, they can be used to inactivate a target locus that is functionally haploid in the targeted line the ploidy of a gene of interest is not always obvious from either karyotype or Southern analysis. Thus, we have successfully used parahomologous targeting to generate a Kc line that is deficient in EcR function Kc cells are diploid for chromosome III (on which EcR is located), but they contain four copies of EcR, of which only one is functional (Cherbas and Cherbas 1997). 

By counting chromosomes, different levels of the ploidy [e. g., n = haploid, 2n = diploid (the normal two sets of chromosomes), 4n = tetraploid, 6n =... 

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