Question

What three essential criteria must be met in order to execute a successful mapping cross?

Short answer

Answer: The three essential criteria for a successful mapping cross are linkage, recombination, and large sample size.

Step-by-step solution

1. Linkage

The genes involved in the mapping cross should be linked, meaning they are located on the same chromosome or closely positioned together. This is crucial for determining genetic distances between those genes and observing the effects of recombination.

2. Recombination

The purpose of the mapping cross is to observe the frequency of recombination among offspring, which reflects the relative distances between the genes. To achieve this, the mapping cross must be set up in such a way that genetic material is exchanged between homologous chromosomes during meiosis, leading to the production of recombinant gametes. Parents involved in the cross should have different alleles for the genes being studied, allowing for clear observation of recombination events in the offspring.

3. Large Sample Size

In order to obtain accurate and reliable results, a large number of offspring must be produced and analyzed for their gene combinations. A larger sample size minimizes the effects of random chance and provides a more accurate representation of recombination frequencies and genetic distances. It also ensures that rare recombination events are adequately represented in the results.