Genes E and H are syntenic in an experimental organism with the genotype EH/eh. Assume that during each meiosis, one crossover occurs between these genes. No homologous chromosomes escape crossover, and none undergo double crossover. Are genes E and H genetically linked? Why or why not? What is the proportion of parental gametes produced by meiosis?

Verified step by step guidance

1. span>1. Understand the concept of synteny: Genes E and H are located on the same chromosome, which means they are syntenic. This is a key factor in determining genetic linkage.</span
2. span>2. Define genetic linkage: Genes are considered genetically linked if they are located close to each other on the same chromosome and tend to be inherited together because they do not assort independently.</span
3. span>3. Analyze the crossover scenario: Since one crossover occurs between genes E and H during each meiosis, this will affect the linkage. A crossover event can separate linked genes, leading to recombinant gametes.</span
4. span>4. Determine the proportion of parental gametes: In this scenario, since one crossover occurs, half of the gametes will be parental (EH and eh) and half will be recombinant (Eh and eH). This is because each crossover event results in two parental and two recombinant chromatids.</span
5. span>5. Conclude on genetic linkage: Despite being syntenic, genes E and H are not genetically linked in this scenario because the crossover ensures that parental and recombinant gametes are produced in equal proportions.</span

Key Concepts

Genetic Linkage

Genetic linkage refers to the tendency of genes located close to each other on the same chromosome to be inherited together during meiosis. When genes are syntenic, they are physically located on the same chromosome, which can lead to a lower frequency of recombination between them. If genes E and H are genetically linked, they will produce more parental gametes than recombinant gametes due to their proximity.

Crossover and Recombination

Crossover is a process during meiosis where homologous chromosomes exchange segments of genetic material, leading to genetic recombination. In this scenario, with one crossover occurring between genes E and H, the resulting gametes will include both parental types and recombinant types. The frequency of these types depends on the distance between the genes; closer genes result in fewer recombinant gametes.

Parental and Recombinant Gametes

Parental gametes are those that contain the original combinations of alleles from the parents, while recombinant gametes have new combinations due to crossover events. In the case of the genotype EH/eh, if one crossover occurs between E and H, the expected ratio of parental to recombinant gametes can be calculated. This ratio helps determine the genetic linkage and the degree of recombination between the genes.