Dr. David Holding is thinking about the role of linkage in these corn traits. He believes there could be two genes that are close together on a single chromosome that causes the offspring phenotype for our Red, Plump x White, Shrunken cross to make offspring that are usually the same phenotype as the parents.

Using staining and microscopes, cytogeneticists have observed ten pairs of chromosomes in the somatic cells of corn. Corn has countless traits controlled by tens of thousands of genes. Since genes are on chromosomes, it makes logical sense that each chromosome is made of thousands of genes. When genes are on the same chromosome they will travel together as the chromosome is passed on to the gametes. If the gene for red vs. white kernel color is on the same corn chromosome as the gene for plump vs. shrunken, those genes will travel together during gamete formation. This could explain why the red and plump gene alleles are inherited together. The same would be true of the white and shrunken alleles on the homologous chromosome in the F1. Therefore, we could explain the phenotype patterns in the offspring with linkage. That is, a separate gene pair controls each trait, but these genes are located near each other on the same chromosome.