Question

You have discovered a special dye that reveals the position of recombination sites on meiotic chromosomes. You use this dye to count the number of recombination sites and then compare this to the number of genetic exchanges that you can detect by looking at the segregation of markers across the genome. You find many more recombination sites as compared to genetic exchanges. Explain this result.

Answer 1

The detection of more recombination sites than genetic exchanges during meiosis suggests that not all recombination events lead to observable crossover or they may be resolved without changing linked alleles, making them undetectable with certain markers.

Step-by-step explanation:

Discovering many more recombination sites in comparison to the actual number of genetic exchanges could be explained by noting that not all recombination events lead to a crossover that results in exchange of genetic material detectable as nonparental phenotypes. During meiosis, chromosomes undergo multiple rounds of recombination, which can lead to the formation of a high number of recombination sites.

However, these recombination events might resolve without an actual genetic exchange, or may result in exchanges that do not segregate away from other linked alleles, and thus are not detectable by analyzing the segregation of specific genetic markers. This occurrence highlights the complex nature of meiotic recombination, where visible chromosome structure and genetic outcomes do not always correspond directly.