Drosophila may be monosomic for chromosome 4, yet remain fertile. A recessive mutant for bent bristles is identified on chromoso
me 4. Determine the genotypes of the F1 and F2 progeny for the following crosses. The following cross is conducted of true-breeding adult flies: monosomic bent bristles x diploid normal bristles. Select the two F1 genotypes that will be produced from this cross
a. -/b+
b. -/b
c. b/b
d. b/b+
e. b+/b+
The answers are: <span>a. -/b+ </span><span>d. b/b+</span>
b+ - the allele for normal bristles b - the allele for bent pristles
Monosomic means there is only one instead of two alleles in a gene locus. So, the parents' genotypes are: <span>monosomic bent bristles: -/b </span><span>diploid normal bristles: b+/b+
</span><span>The following cross is conducted of true-breeding adult flies: Parents' phenotype: monosomic bent bristles x diploid normal bristles Parents' genotype: -/b x b+/b+ F1 generation: -/b+ -/b+ b/b+ b/b+</span>
