Gene R and gene T are genetically linked. Answer the following questions concerning a dihybrid organism with the genotype Rt/rT:

Can you make a general statement about how the occurrence of two crossover events between a given pair of linked genes affects the estimate of recombination frequency? (Hint: Think about this problem for a gene pair with a small recombination frequency versus a gene pair with a much higher recombination frequency. See also Figure 5.10.)

Key Concepts

Genetic Linkage

Genetic linkage refers to the tendency of genes located close to each other on a chromosome to be inherited together during meiosis. This occurs because linked genes are less likely to be separated by recombination events. Understanding linkage is crucial for predicting inheritance patterns and calculating recombination frequencies, which indicate how often genes are separated during gamete formation.

Recombination Frequency

Recombination frequency is a measure of the likelihood that two genes will be separated during meiosis due to crossing over. It is calculated as the number of recombinant offspring divided by the total number of offspring. A low recombination frequency suggests that genes are closely linked, while a high frequency indicates they are further apart, allowing for more frequent crossover events.

Crossover Events

Crossover events occur during meiosis when homologous chromosomes exchange segments of genetic material. The number of crossover events between linked genes can significantly influence the recombination frequency. In cases with two crossover events, the likelihood of producing recombinant gametes increases, which can lead to a more accurate estimate of the genetic distance between the genes involved.