Genetic Traits in German Cockroaches: A Reflective Analysis
What are the genetic traits of a German cockroach with the genotype bu+ bu cv+ cv in repulsion?
Which of the following sets of genes will be found in the most-common gametes produced by this cockroach?
a. bu+ cv+
b. bu cv
c. bu+ bu
d. cv+ cv
e. bu cv+
Answer:
e. bu cv+
In German cockroaches, the bulging eyes (bu) are recessive to normal eyes (bu+) and curved wings (cv) are recessive to straight wings (cv+). Both traits are encoded by autosomal genes that are linked. The given cockroach has the genotype bu+ bu cv+ cv, with the genes in repulsion.
The genes bu+/bu and cv+/cv are autosomal and linked, meaning each homologous chromosome carries an allele of both bu+/bu and cv+/cv genes. In the case of this cockroach, it is heterozygous for both genes, with them in repulsion. This results in one homologous chromosome having a dominant allele for one gene and a recessive allele for the other, and the opposite arrangement on the other homologous chromosome.
Therefore, the genotype of the cockroach can be represented as [bu+ cv / bu cv+]. The most common gametes produced will be the parentals, where there was no crossing-over between homologous chromosomes, maintaining the same distribution of alleles as the parental individual.
As a result, the most common gametes produced by this cockroach will be:
bu+ cv
bu cv+