In tomatoes, the allele T for tall plant height is dominant to dwarf allele t, the P allele for smooth skin is dominant to the p allele for peach fuzz skin, and the allele R for round fruit is dominant to the recessive r allele for oblong fruit. The genes controlling these traits are linked on chromosome 1 in the tomato genome, and the genes are arranged in the order and with the recombination frequencies shown.

What are the genotype and phenotype of the F₁ progeny of this cross?

Key Concepts

Dominance and Alleles

In genetics, dominance refers to the relationship between alleles, where a dominant allele masks the effect of a recessive allele in a heterozygous genotype. For example, in tomatoes, the allele T for tall plants is dominant over the recessive t for dwarf plants. This means that if an individual has at least one T allele, it will exhibit the tall phenotype.

Genotype and Phenotype

Genotype refers to the genetic makeup of an organism, specifically the alleles present for a given trait, while phenotype is the observable expression of those traits. In the context of the tomato cross, the F₁ progeny will have a specific genotype based on the alleles inherited from the parents, which will determine their phenotype, such as tall or dwarf, smooth or fuzzy skin, and round or oblong fruit.

Linked Genes and Recombination

Linked genes are genes located close together on the same chromosome, which tend to be inherited together during meiosis. The recombination frequency indicates how often crossing over occurs between these genes, affecting the genetic variation in the offspring. Understanding the arrangement and recombination frequencies of the genes for height, skin texture, and fruit shape in tomatoes is crucial for predicting the genotypes and phenotypes of the F₁ progeny.