Question

If recombination occurred in 100% of the meiotic cells then what would be the percentage of the recombinant chromosome?"

Answer 1

If recombination occurred in 100% of meiotic cells, 50% of offspring would be recombinants as this mimics the scenario where genes are perfectly unlinked, with every allele combination represented equally.

Step-by-step explanation:

If recombination occurred in 100% of the meiotic cells then the percentage of recombinant chromosomes would be 50%. Recombination is the process by which chromosomes exchange genetic material during meiosis, leading to new combinations of alleles which are termed recombinant chromosomes. As per Alfred Sturtevant's genetic linkage theory, a recombination frequency of 0.5 indicates that 50% of offspring are recombinants, assuming perfect unlinked genes which is the case when recombination occurs 100% of the time or if the genes lie very far apart on the same chromosome or on different chromosomes.

The actual recombination frequency observed for certain traits, such as fruit fly wing length and body color observed by Thomas Morgan, was 17%, indicating that the genes are on the same chromosome and crossover occurs some of the time. However, if 100% of cells experienced a recombination event, we would expect to see a 50% frequency of recombinants, as this would mirror cases where genes are perfectly unlinked. Therefore, in such a scenario, every type of allele combination is represented with equal frequency amongst offspring.

Answer 2

If recombination occurred in 100% of the meiotic cells, the percentage of recombinant chromosomes would be 50% as it leads to a 1:1 ratio of recombinant and parental chromatids. In practice, recombination frequency varies and is used to study genetic linkage and the distance between genes; full recombination in all meiotic events is not natural.

Step-by-step explanation:

If recombination occurred in 100% of the meiotic cells, then the percentage of the recombinant chromosome would presumptively be 50%. This is because recombination occurs during meiosis, leading to the exchange of genetic material between homologous chromosomes. Therefore, for each pair of chromosomes involved in recombination, there would be one recombinant and one parental chromatid, resulting in a 1:1 ratio, or 50% recombinants. However, it's important to note that such a scenario with 100% recombination in meiotic cells does not naturally occur. Typically, the recombination frequency reflects the genetic distance between two genes on the same chromosome.

Thomas Morgan observed a recombination frequency of 17% for specific fruit fly traits, indicating that the genes for those traits were linked and recombination did occur but not in all meiotic events. Similarly, Alfred Sturtevant's work using genetic maps found that genes can range from being perfectly linked (recombination frequency = 0) to perfectly unlinked (recombination frequency = 0.5). A frequency of 0.5 indicates that genes are either on different chromosomes or are very far apart on the same chromosome, making recombinant offspring as frequent as parental ones.

While recombination frequencies less than 50% indicate linkage, it's also posited that very high recombination frequencies approaching 50% could be due to genes located very far from each other on the same chromosome or on different chromosomes, reflecting the idea of independent assortment as per Mendelian genetics.