What is the configuration called when both dominant alleles are on the same chromosome?

The configuration when both dominant alleles are located on the same chromosome is referred to as cis-configuration. In this context, "cis" originates from Latin, meaning "on this side of." It is important in genetics because it indicates that the alleles are inherited together, affecting their phenotypic expression and illustrating how traits can be linked during inheritance.

In cases of gene linkage, understanding whether alleles are in cis or trans configuration can influence the prediction of offspring genotypes in genetic crosses, particularly when assessing traits governed by closely linked genes. The relationship between dominant alleles in cis-configuration can impact the likelihood of traits appearing together in the phenotype.

By contrast, trans-configuration refers to a scenario where the dominant alleles are located on opposite chromosomes, which would facilitate independent segregation during meiosis. This distinction is crucial for interpreting genetic inheritance patterns and for understanding how traits may be passed on through generations.