Question

when does crossing over take place in haploid organism​

Answer 1

Answer:

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Explanation:

Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids

Answer 2

Answer:

Mitotic crossing-over occurs only in diploid cells such as the body cells of diploid organisms. (In order to study mitotic crossing-over in a haploid organism, diploid cells have to be created artificially.)

Let’s look at an example from Drosophila involving the linked genes for body color (y+ = brown, y =  yellow) and hair shape (sn+ = straight, sn = singed or wavy). A fly that is a trans dihybrid for these alleles . A trans dihybrid should express the dominant phenotypes for both genes in cells all over the body. This indeed will be the case for most cells. However, if a mitotic crossover occurs, this can result in the production of homozygous allele combinations in all heterozygous genes that are located on that chromosome arm distal to the crossover (that is, on the portion of the arm beyond the crossover in a direction away from the centromere). Therefore, recessive alleles will be expressed unexpectedly in the phenotype. Because the cells that are products of a mitotic crossover will produce a group of descendent cells that tend to remain together during development, the recessive phenotypes will be expressed as patches or spots on the body. In the example in Figure 5-16, a twin spot of recessive phenotypes is produced by a crossover between the centromere and the nearest locus, and a single yellow spot is produced by a crossover between the loci

Explanation: